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Proceedings of the Chemical Society. September 1961 |
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Proceedings of the Chemical Society ,
Volume 1,
Issue September,
1961,
Page 321-356
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PROCEEDINGS OF THE CHEMICAL SOCIETY SEPTEMBER 1961 CENTENARY LECTURE* Charge Transfer in Organic Solids Induced by Light By A. TERENIN (UNIVERSITY U.S.S.R.) OF LENINGRAD Organic Dyes as Semiconductors.-The present Lecture is devoted to the intermolecular exchange of electrons in organic dyes in the solid state detected by measurements of photoconductivity . During the last decade a renewed interest has arisen in the semiconducting properties of organic solids a subject nearly 50 years old which has not attracted much attention for a long time. In fact after the pioneering researches of Volmer on anthracene in 1915 of Schodro in 1919 on dyed collodion films and of Petrikaln in 1930 on solid dye films,l it was only in the forties that the research in the field was reopened by Eley in this country2 and by Vartanian and Putzeiko in the author’s labora- t~ry.~-~ We are witnessing at present a nearly ex- ponential growth of papers on this subject mostly published in chemical periodicals.Let me mention here the outstanding contribution in this country by Eley on proteins and amino-acids by Northrop and Simpson and by Lyons in Australia and by Schneider in Canada on the aromatic hydrocarbons by Ubbelohde and Eley and their associates on organic complexes. It is impossible in the short time available to give even a brief survey of the present state of the prob- lem. I am sorry but I shall limit my presentation to our own field of research of the photoelectronics of organic dyes and coloured compounds.These are generally investigated in the form of microcrystalline or amorphous films deposited either from saturated solutions or by sublimation on to a gap between two efectrodes. Practically all classes of the dyes-cationic anionic or non-ionic-xhibit in the dark a small conductivity when a potential gradient of about lo00 v cm.-l is applied to the solid film. The d.c. specific conductance u has been found to lie in the range from lo-’ to 10-14 ohm-l cm.-l at 20” in vacuu. As examples we may cite the data in Table 1 from the work of Vartanian and his co- authors.6 * Delivered before the Chemical Society at Burlington House London W.l on March 16th 1961. Petrikaln,Z. phys. Chem. 1930 B 10,9. Eley Nature 1948 162 819; Eley Parfitt Perry and Taysum Traw.Furaday SOC.,1953 49 79. Vartanian and Terenin J. Phys. (U.S.S.R.) 1941 4 173. Vartanian Acfa Physicochim. 1947 22 201. Putzeiko Doklady Akad. Nauk S.S.S.R. 1948 59,471 ; 1949 67 1009. Vartanian Izvest. Akad. Nauk S.S.S.R. (Phys.) 1952 16 169; 1956 20 1541; 1957 21 523; J. Phys. Chem. (U.S.S.R.) 1946 20 1065; 1948 22 769; 1950 24 1361; 1953 27 272; 1957 31 1792; Vartanian and Karpovitch J. Phys. Chem. 1958 32 178 274 543; Vartanian and Karpovitch Doklady Akad. Nauk S.S.S.R. 1956 111 561; 1957 113 1020; 1957 117 57; “Photoelectric and Optical Phenomena in Semiconductors,”Ed. Akad. Nauk Ukrain S.S.R.,Kiev 1959 p. 290; Vartanian and Rosenstein Doklady Akad.Nauk S.S.S.R.,1959 124,295. 321 PROCEEDINGS For the inorganic semiconductors the values of o dark conduction and the minimum quantum of occupy the broad range from 105 to 10-lo ohm-l excitation energy which can be imparted to the dye cm.-l.This comparison shows that organic dyes film by light.* For other dyes the agreement is not assume in respect to electron “transmissivity” an so good and the values of Ed fall short of the onset intermediate place between typical semi-conductors of the absorption and photoconduction spectrum. TABLE1. Crystal Violet rm= I O-’O Indigo -I3ccm=10 Violanthrone Qz0 = 10-4 and insulators. In contrast to the dyes uncoloured organic compounds such as artificial and natural polymers possess in the dry state at room tempera- ture a specific conductance below ohm-l cm.-l in common with typical insulating dielectrics? The dark d.c.conductivity of the dyes increases exponentially with temperature giving a linear rela- tion between In o and the reciprocal (1/T) of the absolute temperature known for the intrinsic semi- conductors viz ln cr = In uo -E&kT. . . . (1) Here (J,,is the pre-exponential frequency factor k the Boltzmann constant and Ed the activation energy of the thermally induced release of charges in the solid in the dark. As can be seen from the plots in Fig. 1 taken from the work of Vartanian,’ measurements of the dark conductance between -100” and +200” fit the linear relation (1) excellently. The values of the activation energy Ed deduced for some dyes are given in Table 2 expressed as usual in ev.In the last column of the Table are given for comparison the magnitudes of the quantum thres- hold hvo of the photoconduction which generally coincides with the onset of the absorption spectrum 2- 2Na+ -1-Phthalocyanines Q20=10-12-10-13 (M = 2~. ~g ,Zn) 104/Temp. (” K) 22 24 26 28 30 32 34 2.5 4 15 FIG.1. Temperature-dependenceof the d.c. dark con- duction current i for dye _films in vacuo. The figures in parentheses below are the activation energies Ed (in ev)from the slope of the graphs. 1 Erythrosine (2437). 2 Rose Bengal (2-0). 3 Phloxine (2.08). 4 Eosine (2.10). 5 Turquoise Blue (1.63). 6 Rhodamine 5G (1.93). 7 Tripaflavine (2.24). 8 Sodium fluorescein (2.03). 9 Cyanine (1.90).10 Chlorophyll (2.00). of the dye film. It will be noticed that for this selec- 11 Indigo (1.75). 12 Pinacyanol (1.80). 13 Copper tion of dyes there seems to be a close correlation phthalocyanine (1-63). 14 Fuchsin (1.83). 15 Night between the thermal activation energy Ed of the Blue (1-70)(Vartanian). Vartanian Izvest. Akad. Nauk S.S.S.R. 1956 20 154. * Of course if Ed/2 is being replaced in equation (1) by Ed no agreement between Ed and hvowill be found in Table 2. SEPTEMBER 1961 For inorganic semiconductors the value of go,the pre-exponential factor in equation (I) for the dark conduction is directly related to the mobility of the charge carriers.8 The immediate application of the same numerical relation to molecular semiconductors seems not to be warranted.In any case the mobility of the charges is extraordinarily low being on an rates of many physicochemical reactions. On the other hand the phthalocyanines give a = 10-13 but Ed = 1-2-1.7 ev.' Light Induced Currents.-On illumination by visible light the dye films if carefully kept at con- stant temperature exhibit a 1OOO-to 10,000-fold increase in the d.c. conductance relatively to its TABLE 2. Comparison of the thermal activation energy for the dark conduction Ed with the threshold quantum for photoconductivity hvo (Vartanian). Dye class Triphenylmethane (cationic) Xanthen (anionic) Acridine (cationic Cyanines (cationic) 9 ? indigoid (non-ionic) Phthalocyanine (non-ionic) 9 9 9 97 Dye name Crystal Violet Erythrosine Phloxine Rose Bengale Trypaflavine Pinacy anol Orthochrome T Indigo Phthalocyanine (metal-free) Cu phthalocyanine Zn phthalocyanine Ed (ev) hvo (ev) 1-78 1-75 2.07 2-14 2.08 2.08 2.05 2.06 2-28 2.3 1.8 1-77 2.05 2.02 1.75 1.79 1 *7 1.6 1.7 1 63 1.8 1.6 optimistic estimate 10,OOO times less than those for inorganic semiconductors.There exists for organic semiconductors a qualita- t ive connection between u and Ed in the respect that large values of Go are often accompanied by large values of Ed or both are small. For instance the polynuclear compounds give the following values Light off 1 A ,d b 0 2 4 6 0 10 12 Time (min.) FIG.2.Rise of the d.c. photocurrent under illumination and its decay for dye films in vacuo. 1 Pinacyanol. 2 Crystal Violet (Vartanian). (ro = ohm-1 cm.-l Ed = 0.2 ev (cyanthrone); cro = Ed = 0.78 ev (violai~throne);~ by con- trast the values for anthracene are uo = lo2 Ed = 2-7 ev.lo A similar regdarity is well known in the value in the dark. The rise and decay of the photo- current iph for some dyes for (tri- and di-phenyl- methanes1 is Slow. However there are many dyes (PkacYanok Phloxine indigo PhthalocYanines etc.) with a very short relaxation time. Extreme examples ofthe relaxation are !hwn in Fig. 2. a @ C Y L a oc -0.02 stc. FIG. 3. Rise of the photocurrent and its decay under intermittent illumination.a Metal-free phthalo-cyanine. b Copper phthalocyanine. c As b after heating at 150" in air. Initial andfinal time constants of the non-exponential decay are a 1.3 x and 3 x 10-3sec.; b 2 x 10-5and4 x 10-3sec.; c 5 Y and 1.2 x sec. (Putzeiko). * Many Harnik and Garlich J. Chern. Phys. 1955 23 1733. Akamatu and Inokushi J. Chern. Ph-vs. 1950 18 810. lo Innkushi Bull. Chern. SOC.Japan 1956 29 181. PROCEEDINGS By using intermittent illumination and oscillo- graphic recording it has been shown that many dyes and pigments exhibit a very fast initial response to light with time constants between and sec. (Fig. 3). The fast component of the current sorne- times amounts to 80 % of the total photocurrent.ll This signifies that we are dealing with a primary transport of electrons through the organic solids here concerned and not with a conductivity due to the movement of ions.In the simple method of d.c. and a.c. resistivity measurements described above the organic sub- stance is in contact with metal electrodes with the inevitable formation on them of thin transition layers of the chemically changed compound. In the method of diffusion photo-currents widely used by us for a long tirne59l2-l5 the organic film or crystalline powder is inserted into the narrow space between the plates of a condenser being thoroughly insulated from them by thin mica or quartz laminae. The intermittent light entering such a “sandwich” cell through one of the semitransparent plates 600 1010 releases charges in the organic solid which produce Wave Iengt h(my.) an alternating diffusion current without the applica- FIG.4. Magnesium phthalocyanine sublimed $lm. tion of an external field.* As a result a photo-1 Photoelectric sensitivity (photo-e.m.J ; 10-5v) electromotive force (e.m.f.) is generated on the con- spectrum. 2 Absorption spectrum. 3 Absorption denser which can easily be measured. Moreover the spectrum of an acetone solution (10-4~) (Putzeiko). set-up improved by the addition of a phase-sensitive detector allows a direct determination of the sign of the diffusing charges,17 which is of pri-mary importance for an insight into the mechanism of electron transport in organic solids. The spectral dependence of the photo-induced current has been shown to coincide with the absorp- tion spectrum of the organic solids.For example Fig. 4reproduces the spectrum of the photo-e.m.f. induced in a sublimed film of magnesium phthalo- cyanine and Fig. 5 that for a microcrystalline film of chlorophyll a. Phthalocyanines and similar tetra- pyrrole pigments that have been extensively studied by us,I3-l5 show very conspicuously that the band 400 600 800 900 structure peculiar to these molecules in solution is Wavelength (my) retained to some extent in the absorption spectrum of the solid and equally well in the spectrum of the FIG. 5. Photoelectric sensitivity (photo-e.uz1.f.) of a photo-induced current. Although in the solid state the chlorophyll a Jilm in vacuo. l1 Putzeiko Doklndy Akad.Nauk S.S.S.R. 1960 132 1299. l2 Putzeiko J. Phys. Chem. (U.S.S.R.),1948 22,1172; Izvest. Akad. Nauk S.S.S.R. (Plz~s.),1949 13 225; Doklady Akd. Nauk S.S.S.R. 1959 124 796; 1959 129 303. l3 Putzeiko and Terenin J. Phys. Chem. (U.S.S.R.),1956 30 1019. l4Terenin and Putzeiko J. Chim. phys. 1958 55 681. l5 Terenin Putzeiko and Akimov Faraday SOC.Discuss. 1959 27 83. * The method known as condenser method was devised in the thirties by Berginann and his co-workers16 for the study of the inner photoelectric effect in inorganic crystalline semiconductors. Then the method was overlooked until in 1947 we applied it to the study of organic and inorganic semiconductor^.^ 16Bergmann Phys. Z. 1932 33 209; Nuturwiss. 1932 20 15; Bergmann and Hanster 2. Phys. 1936 100 50; Bergmann and Ronge Phys.Z. 1940 41 349. l7 Terenin Putzeiko and Akimov J. Chim. plzys. 1957 54 716; Putzeiko and Akimov “Photoelectric and Optical Phenomena in Semiconductors,” Ed. Akad. Nauk Ukrain. S.S.R.,Kiev 1959 p. 301. SEPTEMBER 196 1 bands are wider than in the solution on account of the strong mutual perturbation of closely packed molecules they unmistakably belong to the indi- vidual molecules of the solid and are not due to a collective response of the whole array of molecules in the organic crystal. This point must be stressed here because we are inclined to speak of conduction bands in the organic semiconductors by analogy with the inorganic ones. However in contrast to the latter with entirely col- lectivised valency electrons in the organic molecular crystals we generally have individual molecular entities connected by ionic hydrogen bonds and van der Waals’ forces but without loss of their in- dividuaIity.It is evident that even in the most favour- able case of easily polarisable dye molecules fusion of the .rr-electron clouds does not occur in the lattice to an extent such that a common intermolecular 3ystem is formed. Of course overlapping of the electron clouds of the molecules is favourable to an intermolecular electron exchange. However these conduction bands if they exist at all must be quite narrow on account of the low mobility of the charge carriers; besides they are not revealed in the struc- ture of the absorption and photoelectric spectrum which remains in the main that of the separate molecules.SigM of ihe Photocurrent Carriers.-Up to the time when the sign of the charges transported in organic semiconductors was elucidated their conduction was attributed to mobile electrons. That this is not generally the case is shown by Table 3 which sum-marises our determinations of the signs of charge carriers of the diffusion photocurrent. It will be seen that most of the ionic and non-ionic dyes as well as the simpler compounds such as anthracene and the tetrapyrrole pigments (phthalocyanines porphyrins chlorophylls) exhibit photocurrent carriers of posi- tive sign. This implies that the electrons released in most of the organic solids investigated are kept im- mobile in some form of trap and that it is the positive electron vacancies at the ground levels of the rnole- cules which are predominantly mobile.This is an unexpected result which cannot be ascribed to the presence of imperfecticns in the organic crystals studied and in particular not to the highly developed surface of the n4crocrystals prone to contamination by such electronegative gas molecules as oxygen of the air. In fact when monocrystals were grown and the measurements were performed in vacuo the sign remained positive. The sign of the diffusing charges has been indepen- dently corroborated by Akimov in my laboratory by 325 measurements of the contact potential change of the surface of the dye films under ill~rnination.~~~~~ Mechanism of Charge Transfer.-The primary act in the molecular lattice of the dyes as judged from the spectrum is excitation of a single molecule in the lattice by the absorbed photon.The excitation quantum can travel as an “exciton” in the array of closely connected molecules (Fig. 6a) even when these do not form a regular lattice as is known for the case of concentrated dye solutions.* When during TABLE 3. Sign of the photocurrent charge carriers in dye films(Putzeiko and Akimov). Di- arzd Tri-phenylmethanes (cationic) Crystal Violet ............................ - -Malachite Green .......................... Brilliant Green.. .......................... + Auramine ................................ + -Aurine (anionic) ..........................Th iazin e (cat ionic) Phenosafranine ............................ + Acriditie (cationic) Trypaflavine .............................. + Xanthen Methyl Eosine B.. -......................... Rhodamine B (cationic) -.................... Phloxine (anionic) ........................ + Indigoid (non-ionic) Indigo..................................... + Indanthrene (non-ionic) Indanthrene G Yellow.,. .................... Indanthrene G Orange ..................... Violanthrone .............................. Cyanine (cntiunic) Cyanine ................................ Pinacy anol ................................ 3,3 ‘-diethyl-thiacarbocyanine iodide. ......... 3,3’-diethyl-5,5’-dinitro-thiacarbocyaninetoluyl-sulphonate ..............................Neocyanine................................ Kryptocyanine ............................ Piztizalocj~artirie (non-ionic) Phthalocyanine metal free. ................. Phthalocyanine Fe3+ Fe2+ Ag+ Co2+,Cu2L Mn2+,h4g2+,Zn2+ Fe3+ (sulph.) Cu2+ (sulph.) Methylchlorophyllide (a + b) .............. Chlorophyll (a +b) ...................... Protoporphyrin ............................ Hzmatoporphyrin ......................... Hzmin ................................... Anthracene ............................... Akimov Doklady Akad. Nauk S.S.S.R. 1959 128,691. * It must be emphasised that contrary to the cases anthracene and other luminescent crystals the exciton migrating in solid dyes cannot cover large distance on account of the known strong concentration quenching of the fluorescence even in solution.this “exciton” migration a structural defect such as the surface of the microcrystal or an impurity centre is encountered one of the charges of the “exciton,” or both are set free (Fig. 6b). In com- pounds with the semiconductivity of the positive (p-)type considered above sorbed oxygen quinone or other electron-accepting molecule does function as an electron trap whereas the positive hole remain- ing at the ground level of the molecule is set free to FIG.6. Schematic diagram for the exciton migration (a) electron capture (b) and positive-hole migration (c) and (d). migrate. This migration is produced by filling up the electron vacancy by the next neighbour from its ground-state orbital and a continuation of this process resulting in a kind of relay race between molecules (Fig.6c,d). Of course this is only a primi- tive description of a part of the processes that occur. The reaction is in principle identical with that known to occur in solutions between electron- donating (i.e. reducing) and oxidising molecular species. We thus aciually observe an oxidation-reduction process between identical organic mole- cules in the solid. When the mobile carriers of the photocurrent are negative the intermolecular elec- tron interchange must of course involve some upper levels of the solid the electron changing its host. It is in fact the intermolecular migration of a surplus electron in a very narrow conduction band as said before even in the very favourable case of dye crystals.In the first presentation of the electronic pheno- mena in organic solids by the authorlg the idea was advanced that the conducting electron might be transported at the vacant triplet levels of the mole- PROCEEDINGS cules merging as supposed into a kind of a triplet conduction band the singlet excited level remaining unaffected as shown by the absorption spectrum.* This suggestion has been upheld in the recent papers by Rosenberg.21 The approximate equality of the activation energy Ed of the dark conduction and the height of the singlet excited level Izv6 (Table 2) seems to disprove such a possibility. Moreover Vartanian TABLE 4.First absorption maximum hvl (in solutions) ionisation potential Iph in the gas phase and their diference for a series of compounds. All values in ev (Vilessov). Compound Benzene Naphthalene Anthracene Naphthacene Pyridine Quinoline Acridine Benzoquinone Anthraquinone Benzaldeh yde Acetophenone Benzophenone a-Naphthylamine P-Naphth ylamine Aniline Stil bene Diphenylbutadiene Rhodamine 6G Indigo Meroc yanine Quinoline Blue Pinacyanol _____ -kv1 4-9 lph 9.2 Iph-]/vl4.3 4-0 8-1 4.1 3.3 7.4 4.1 2-6 6-9 4.3 5.0 9.4 4.4 4.0 8.3 4.3 3.6 7-8 4-2 3.4 9.7 6.3 3.2 9-3 6-1 3-8 9-6 5.8 3.9 9.6 5.7 3-7 9.4 5.7 3.9 7.3 3.4 3.7 7-2 3.5 4.4 7-7 3.3 4.2 7.5 3-3 3-5 7-3 3.8 2-55 7-26 4.9 2.3 7.17 4.9 2.45 7-35 4.9 2.3 7.35 5.0 2.05 7.25 5.2 and Rosenstein6 recently showed for simple phos-phorescent organic crystals (benzophenone phthal- imide etc.) that Ed is close to the height of the singlet level and definitely higher than the triplet level.Energy Requirement for Electron Release.-The energy of the photon necessary to ionise a gaseous organic molecule is very well known from the work lg Terenin Radiotechn. i Elektron (U.S.S.R.),1957 1 1127. * The low probability of the transition between the ground-singlet and ground-triplet levels does not precludc. a very effective energy transfer at the dose intermolecular distance in the solid (cf. ref. 20). Terenin Faraday SOC.Discuss.,1959 27 97.21 Rosenberg J. Chem. Phj~.,1958 29 1108; 1959 31 238; J. Opt. Soc. Arner. 1958 48 581. SEPTEMBER 196 1 327 of Price in this country.22 Its magnitude is very high in the molecule has a definite probability of being amounting to 7-10 ev and requiring the shortest trapped in the lattice and therefore of giving rise to ultraviolet range for the photoionisation. a hole migration.* Vilessov and the have remeafured the The quantum yield of the electron release by light photoionisation thresholds for a series of aromatic in organic solids is generally very low. For the poly- compounds and extended these measurements to nuclear hydrocarbons and acridine it amounts to some dyes in the gas phase (Table 4). As will be seen only 10-5-10-9 even for monocrystals.26 For the TABLE 5.Photoelectron emission threshold 4(work function) onset of the absorption spectrum hvo electron affinity x = 4 -hvo for the dye films; photoionisation potential Iph of the gaseous dye molecule. All values in ev (Vilessov). Dye 4 hvo X Eosine 6.15 2.1 Er ythrosine 5.8 (4.7) 2.2 3-6 (3.1) Quinoline Blue 5.4 2.0 3.4 7.35 1-95 Pinacy anol 5.0 1-8 3.2 7-28 2-28 Merocyanine 5.2 2.3 2.9 7-35 2-15 Pinakryptol Green 5.2 1.8 3.4 Pinakryptol Yellow 5.4 2-1 3.3 Methylene Blue 5-0 1-8 3.2 Alizarine Blue 54 1.8 3.6 7.35 1-95 Rhodamine 6G 5.7 3.1 3.6 7.26 1.56 Rhodamine B 5.2 2-2 3.0 Indigo Blue 4-9 1.8 3.1 7.17 2.27 /3-Carotene 5.5 2-4 3-1 Chlorophyll (a + b) 4.8 1.6 3.2 Phthalocyanine (metal-free) 6-0 1-7 4-3 Zn phthalocyanine 6.0 1-6 4.4 from the last section of the Table the work Iph dyes it is higher amounting to ca.0.1% and in required to split an electron from a dye molecule in extremely thin dye films the quantum yield of the vacuo remains in the neighbourhood of 7 ev not- photoconduction increases to 20-30 %.27 For micro- withstanding the low excitation energy Av,. crystalline phthalocyanine the quantum yield of In contrast to this as shown at the beginning of photoconduction is 0-1% according to our measure- this Lecture an electron can be detached from the ments. molecule in the solid state on absorption of only Some estimate of the photoionisation energy for a 2-23 ev or less corresponding to its first absorp- molecule in the lattice can be obtained by measuring tion band.the light-induced emission of electrons from the sur- The possibility of electron release by the excited face of the solid in vacuu which has been recently molecule has been considered in detail by Lyons2* carried out by Vilessov and the author.28 for anthracene. He showed the presence in the mole- The difference between the photoionisation cular lattice of vacant self-trapping levels for the potential of the same dye molecules in the gas phase electron situated below the excited singlet level of the Iph and the quantum threshold of the external photo- molecule. By an electron transfer from one molecule electric emission (work function +) gives an insight to a neighbour a large amount of polarisation energy into the magnitude of the compensating polarisation of the crystal lattice is evolved which partly com- energy evolved when an electron is detached from a pensates for the high ionisation energy of the mole- molecule in the Iatti~e.~**~~ This difference according cule.Thus according to Lyons the excited electron to our results given in Table 5 amounts to about 22 Price Chem. Rev. 1947,41,257; Conf. Molecular Spectroscopy London Feb. 1958 ed. Thornton and Thompson, London 1959. 2s Vilessov and Terenin Doklady Akad. Nauk S.S.S.R. 1957 115 744; Vilessov ibid. 1960,132 632 1332. 24 Lyons J. 1957 5001 ; Austral. J. Chem. 1957 10 365. 25 Riehl Nuturwiss. 1956 43 145. 26 Lyons and Morris J. 1957. 3665. *? Nbddack Eckert and Meier Z. Elektrochem. 1952,56 1735; Noddack Meier and Hans Z.phys. Chem. (Liep-zip) 1959 212 55. I,. 28 Vilessov and Terenin Dokludy Akud. Nuuk S.S.S.R. 1960 133 1060; 1960 134 71. 29 Murrell Discuss. Faraduy SOC.,1960,28 76. * The formation of ion pairs in the organic solid as mechanism for its conduction has been considered by RiehLS5 328 1.5-2 ev. An equal polarisation energy is addition- ally evolved when the neighbouring molecule is charged. The sum of these energies 3-4 evplus the electron affinity of the accepting molecule (probably ca. 1 e~~~), is so large that the existence of electron attachment levels in the dye lattice lying below the singlet level is also plausible for solid dyes. We consider ourselves therefore entitled to use Lyons's scheme for anthracene equally for dye semi- conductors of thep-type.For those of n-type with electrons as the mobile charge-carriers the mechan- ism of intermolecular electron exchange seems to be that considered by Northrop30 and Rieh1.25 IIII 0 60 I20 180 Time (min.) PROCEEDINGS conductivity type the conduction and photo-diffusion currents are enhanced by sorption of oxygen benzoquinone acting as additional trap.4>14 The photo-processes considered in this Lecture are at first sight not photochemical in the strict sense of the word. No permanent chemical change of the solid remains after the illumination provided this was not unduly intense and the ultraviolet range was excluded. However depending on the ambient atmosphere or traces of gases definite photochemical changes can be detected by the conduction method.In the presence of oxygen illumination of the dye film by visible light produces a gradual surfacial 0 30 0 30 60 0 30 033 Time (min.) FIG. 7. Action of Hg vapour (2 x lop3mm.) on the photoconduction of a fuchsin film. a Admission of Hg vapour does not have any action on the decaying condiction but the photoconduction is strongly increased. b 1 Photoconduction of the Jilm in vacuo; 2 the same after the removal of Hg vapour admitted in the dark; 3 photoconduction in the presence of Hg vapour; 4 freezing out of the vapour; 5 light switched cfi 6 after heating in vacuo at + 100". An ordered array of molecules is not absolutely necessary for an electron interchange as shown by the conduction of molten naphthalene and the fact that none-crystalline sublimed dye layers exhibit a marked photoconduction and photo-e.m.f.It may be mentioned that n-and p-type photo- conduction in dyes reveal the existence of a thermal energy of activation Eph which lies between 0-2 and 0.3 ev.6 Action of Gases.-The ambient gas atmosphere produces a marked influence on the photoconduction of organic solids. As shown very early by Vartanian? oxygen iodine or benzoquinone (i.e. electron acceptors) reversibly depress the photoconductivity and also the decaying after-conduction in the dark for n-type dyes evidently trapping the migrating electrons. On the other hand for dyes of thep-semi-so Northrop Proc. Phys. SOC.,1959 74 756. a1 Vartanian Dokladv Akad.Nauk S.S.S.R. 1954 94 829. oxidation which can be detected very sensitively by a drop in the dark cond~ction.~ A remarkable instance of a reversible photoreaction has been observed by Vartanian for fuchsine:31 in the presence of mercury vapour at room temperature (pressure ca. 2 x mm. Hg) the conduction of the fuchsine film is enhanced by two orders of magnitude but under illumination only (Fig. 7). Dyes exhibiting this phenomenon besides fuchsine are only those un- alkylated amino-groups such as Phenosafranine Safranine T Thionine etc. Similar dyes but with alkylated amino-groups such as Crystal Violet Capri Blue the Rhodamines Auramine etc. are inactive. Mercury atoms by forming complexes with the amino-groups form a doped photoconductor with enhanced sensitivity.Other examples could be cited SEPTEMBER 1961 329 -Amethyst Violet Crysta I Violet Fuc h sine Capri Blue Thiont ne Safranine T but this constitutes a new subject outside the scope of this Lecture. An especially interesting oxidation-reduction reaction arises when the photoconductive dye film supported on a metal electrode is being immersed in an electrolyte solution. As was shown by Evstigneev and the author in 1951,3 such a supported film of phthalocyanine or chlorophyll pigments imparts to the electrode on illumination a positive or negative potential depending on the presence of electron- accepting or -donating molecular species in the electrolyte solution (Fig. 8). It was shown that the seat of the photovoltaic reaction is at the interface between the semiconducting pigment and the electrolyte.Conclusion.-This brief survey of our contribution to the field of organic photo-semiconductors during the past 20 years shows that starting from a physical approach to the problem we were inevitably driven to the photo-chemical and even photo-biochemical aspects of the phenomena of electron interchange between organic molecules. 32 Evstigneev and Terenin Dokladv Akad. Nauk S.S.S.R. The researches described above have been carried out by Dr. Vartanian and my associates Dr. Putzeiko Dr. Akimov and Dr. Vilessov in my laboratory. N-KCl Quinol ,Ascorbic acid FIG. 8. Photo-induced potential on an eleciuode supporting a phthalocyanine or chlorophyll film immersed in an electrolyte aqueous solution.1951 81 223. COMMUNICATIONS Rotational Analysis of the C lnU-X lCg+ System of K, and the Ionisation Potential of K By E. W. ROBERTSON and R. F. BARROW CHEMISTRY OXFORD (PHYSICAL LABORATORY UNIVERSITY) RECENT work1* on Li and Na has shown that their Rydberg series of ln,states from which it is possible prominent shorter-wavelength absorption band to derive estimates of the ionization potentials of systems arise from transitions C,D 'nutX lC,+. these molecules. In fact the states B,C,D . . .appear to constitute a We have now examined the rotational structure of Barrow Travis and Wright Nature 1960 187 141. Velasco Andes real. SOC.espafi. Fis. Quim. 1960 A 56 175.330 several bands of the C-Xsystem of K which lies in the region 4200-4500 A. The bands were photo- graphed in absorption on Kodak XI a0 plates in a third order of a 6.5-m. concave grating spectrograph. The large number of rotational levels populated and the overlapping of bands of different sequences made analysis difficult and it was fortunate that reliable values of the ground-state rotational and vibrational constants were a~ailable.~ It was possible however to pick out relatively strong Q branches showing in the case of unblended lines the expected alternation of intensity. (l-type doubling was negligibly small so that the extension of the analysis to include R and P branches was relatively simple. In all ten bands lying in the region 22,955-22,695 cm.? were analysed.Constants (in cm.-l) derived for the state C are as follows An earlier vibrational analysis is The presence of a strong Q branch together with weaker R and P branches indicates that the transition is 1n-lz+. The fact that the system appears to be of normal intensity indicates an allowed transition the character of the C state of K is therefore lnu. It is then most probably analogous to the C lfl states of Li and Na,. There is very strong evidence-for example from a comparison of thermochemical and spectroscopic dissociation energies-that the states Binu of the alkali-metal molecules are to be cor- related with M(ns2S) + M(np2P).The most reason- able assumption1s2 about the C states is that they are derived from M(ns 2S) + M( (n + 1)p ,P),so that the B,C,D ... states constitute a Rydberg series of (sug,nprr,) lflU states. In the case of Li, this series can be extrapolated to give an ionisation potential (Li,) N 40,OOO cm.-l while for Na a rather more certain extrapolation yields 39,300 cm.-l. A comparison of the relevant atomic and molecular term values is given in Table 1. These figures indicate that the molecular term-values approach more nearly to the atomic term- values (i) as the quantum number increases and (ii) as the atomic number and thus the internuclear distance increases. We can use these conclusions to Loomis and Nusbaum Phys. Rev. 1932 39 89. PROCEEDINGS estimate term values for the B and the C state of K, these lead (Table 1) to an ionisation potential (Ka 21 33,000 cm.-l.TABLE 1. Atomic5and molecular term values. Li 2P 3P 4P 28,583 12,562 7017 Li 19,560 B 9450 C 5865 D cnol.lTatom 0.68 0.75 0.84 Na 3P 4P 5P 24,485 1 1,180 6409 Na2 B C D Tmol.IZTtom 18,980 0.78 9910 0.89 5860 0.91 K 4P 5P rmol./ Tatom Tmol. Ionisation 22,000 E0.851 [18,700] 10,300 [0*96] [9890] potential (Ka 34,080 32,860 The present values for the atomic I(M) and molecular I(Ma potentials (in cm.-l) are sum-marised in Table 2. TABLE 2. I(M) Z(M.J dZ Li 43,490 40,OOO 3490 Na 41,450 39,300 2150 K 35,010 33,000 2010 Since the difference dZ = I(M) -Z(M2) is equal to the difference in dissociation energy D(M,+) -D(M,) it is concluded that in all cases the ground- state dissociation energies of the ionised molecules are greater than those of the neutral molecules although the neutral molecules possess larger force constants and smaller internuclear distances in their ground states.This conclusion is at first sight sur- prising but it is supported by the results of theoretical calculation^^^^ of the energies of Li and of Li,+ which indicate that Li,+ should be more stable than Li by about 0.48 ev a figure which is in fortuitously close agreement with that obtained spectroscopically namely 3490 cm.-l or 0.43 ev. The calculations indicate that the effect is to be ascribed to repulsion between the valency and the non-bonding electrons. (Received,July 13th 1961 .) Sinha Proc.Phys. SOC.,1948,60,436. Moore “Atomic Energy Levels,” National Bureau of Standards Circular No. 467 Washington. James J. Chem.Phys. 1935,3 9. Faulkner J. Chem. Phys. 1957,27 369. SEPTEMBER 1961 33 1 The Configuration of Furnagillin By N. J. MCCORKINDALE and J. G. SIME DEPARTMENT GLASGOW, (CHEMISTRY THE UNIVERSITY W.2) Ir has recently been shown as a result of series of degradative experiments that the antibiotic fuma- gillin has the constitution (I).l We have conkn~ed this constitution and elucidated the stereochemistry by an X-ray study of the key degradation product "tetrahydroalcohol-Iab" (II; R = H) as its mono- p-bromobenzenesulphonate(I1 ;R = *SO,C,H,Br). The crystals are monoclinic prisms m.p. 103-104" with a = 16.80 A b = 6.12 A c = 11-77A and fi = 97.25".There are two molecules in the unit cell [d (meas.) = 1.38 d (calc.) = 1-40] and the space group is C,2-P21. The 1885 independent structure amplitudes used were obtained by equi- inchation Weissenberg techniques using Mo-K radiation for the h0l zone and Cu-K for the remainder; all intensities were estimated visually. Me The structure was solved by using the heavy atom technique initially for the h0Z projection only. The x-and z-co-ordinates of the heavy atoms were sub- sequently confirmed by computing Patterson sections at y = 0 and y = 4. The choice of p-bromobenzene- sulphonate as heavy-atom derivative of an alcohol has the advantage that the structure factors can be calculated on the basis of the bromine and the sulphur atoms and the two ring carbon atoms to which these are attached thus avoiding the false symmetry centre to be expected in the subsequent Fourier in space group P2, if only the bromine atom is used.When the phase angles obtained on the basis of these four atoms were combined with the structure amplitudes to compute the first three- dimensional Fourier synthesis all of the atoms except one oxygen were located. These positions were then used as the basis for further structure factor and Fourier synthesis calculations. Superirn- posed contour sections illustrating this second Fourier summation are shown in the Figure. The structure factors calculated on the basis of the posi- tions obtained from this Fourier synthesis gave an average discrepancy between observed and cal-culated structure amplitudes of 21 %.Further refinement is being undertaken. The second three-dimensional electron-density distribu- tion for tetrahydroalcohol-Iab mono-p-bromobenzene- sulphonate shown by means of superimposed contour sections pasallel to (010). on tours from 2e/A3 are shown at intervals of le/A3 except on bsomine (l0e/A3). One noteworthy feature in the configuration 011) of tetrahydroalcohol-Iab ester is the environment of the tertiary hydroxyl group. The infrared spectra of the alcohol (Vmax. 3578 and 3492 cm.-l unchanged in relative intensity on dilution) and of its p-bromo- benzenesulphonate (Vmax. 3482 crn.-l) indicate that the tertiary hydroxyl group in these compounds is intramolecularly hydrogen bonded in solution.It is evident from the X-ray structure of the ester that this bond is to the epoxide-oxygen atom. Our present estimate of the 0-0distance concerned is 2-82 A. We are grateful to Professor D. S. Tarbell for suggesting this problem and for supplies of materials and to Professor J. Monteath Robertson for his interest. This work was carried out during the tenure of an I.C.I. Fellowship (by N.J.McC.). (Received July 1Oth 1961.) Tarbell Carman Chapman Huffman and McCorkindale J. Arner. Chern. Soc. 1960 82 1005; Tarbell Carman Chapman Cremer Cross Huffman Kunstmann McCorkindale McNally Rosowsky Varino and West ibid. 1961 83,3096. PROCEEDINGS 3,4-Dimethylenecyclobutene By A.T. BLOMQUIST and P. M. MAITLIS (BAKER OF CHEMISTRY UNIVERSITY N.Y. USA.) LABORATORY CORNELL ITHACA THEonly cyclic isomer of benzene which has hitherto triene in iso-octane has maxima at 248 (log E 4-3) and been described is fulvene. We now report the syn- 211.5 mp (log E 5.0) and is very similar to that thesis of a second isonier 3,4-dimethylenecyclo- reported for l-rnethyl-3,4-dimethylene~yc:obutene.~ butene (I). Molecular orbital calculations1 gave a The position of the long-wavelength band is also resonance energy of 1.21p for this compound very close to that for 1,2-dimethylenecyclob~tane,~ indicating that it should be isolable. By anaIogy with suggesting that both (I) and its 3-methyl homologue p-quinodimethane however the triene would be are not conjugated trienes but rather diems cross- expected to polymerise rapidly.conjugated with a double bond. The pure hydrocarbon (I) b.p. 51 O was obtained 3,4-Dimet h yIenecyclobut ene rapidly absorbed ca. in ca. 1% yield by thermal decomposition under nit- 2.64 mol. of hydrogen in the presence of palladised rogen of 3,4-bis(dimethylaminomethyl)cyclobutene charcoal; the product obtained contained no double bismethohydroxide (11) which was synthesised as bonds and vapour-phase chromatography analysis outlined in the chart from 3,4-dibromocyclobutane- indicated the presence of two compounds presum- 1 ,Zdicarboxylic acid.2 ably cis-and trons-dimethylcyclobu tane. t (8 I '/o> Reagents I PCI, then NHMe,. 2 LiAIH,. 3,Zn-MeOH. 4 Met-AgOH.Infrared spectrum oj3,4-dimethyZenecycEbutene (10cnz. gas cell 20 mm.pressure). I~ I1 I I I I 11 1 1 1 I1 I 3 4 5 6 7 8 9 1011 12 1314 Wuve 1engt h 9) Vapour-phase chromatography of the distilled The triene is a mobile colourless liquid with a hydrocarbon (I) showed it to be homogeneous. The strong olefinic odor which darkens and polymerises infrared absorption spectrum (see Figure) has a rapidly even under nitrogen. In the presence of air strong band triply split at ca. 11-5p similar to that it gives a solid oxygen-containing polymer. Tetra- observed for the exomethylenic groups in 1,2-di- cyanoethylene in tetrahydrofuran reacts with it methylenecyclob~tane,~ and bands at 12-5 p due to giving complex products. the cis-double bond. The intensity of the band at 3.29 p (methylene hydrogen) is as expected approxi- The authors thank the National Science Founda- mately twice that of the band at 3.39 p (cis-double tion for funds in support of this work.bond hydrogens). The ultraviolet spectrum of the (Received June 26th 1961.) Roberts Streitweiser and Regan J. Arner. Chem. SOC.,1952 74 4579. Vogel Annalen 1958 615 7; Blomquist and Cook Chem. and Ind. 1960 873. Blomquist Cook,and Maitlis unpublished results. * Blomquist and verdol J. Amer. Chern. Soc. 1955,77 1806. Williains and Sharkey J. Amer. Chem. SOC.,1959 81 4270. SEPTEMBER 1961 333 Molecdar Dissymetry due to Symmetrically Placed Hydrogen and Deuterium By G. R. CLEMO and R. RAPER (UNIVERSITY OF DURHAM KING'S UPON TYNE) COLLEGE NEWCASTLE A NOTE by Pockerl prompts us to draw attention to the publication by one of us and (the late) A.McQuillen2 in which we reported very similar results in the optical resolution of (&)-a-pentadeuterophenylbenzylamine. The (+)-(hydrogen tartrate) prepared from this had [a],+ 13.2" and gave the oxalate of the (-)-base a; -0.023" -0-017" -0.024" (c 0-4% in alcohol) [a] -2-5" from which the (-)-base itself was obtained having a? -0-14" (c 4-77% in alcohol) [a]g -5-7". From the (-)-(hydrogen tartrate) ([a], -13.2") the (+)-oxalate a 0.013" Pocker Proc. Chem. SOC.,1961 140. a Clemo and McQuillen J. 1936 808. Adams and Tarbell J. Amer. Chem. SOC.,1938,60 1260. Clemo and Swan J. 1939 1960. 0.015" [a] + 2-05" and the (+)-base a 0.041" (c = 1.64% in alcohol) [a]:;+ 5.0" were obtained.In all cases the polarimeter readings were checked (by R.R.) and it is significant that the rotations of the oxalates and free bases were in all cases in the opposite sense to those of the tartrates from which they were obtained. Although Adams and TarbelP and one of us and G. A. Swan4 were unable to confirm these results Pocker's work leads us to conclude that a resolution was in fact effected. (Received,JuZy 14th 1961 .) Preparation of Cyclo-octatetraenes by the Photo-addition of Acetylenes to Benzene By D. BRYCE-SMITH and J. E. LODGE (THEUNIVERSITY, READING) 1,~-PHOTO-ADDITION of maleic anhydride to benz- ene1*2 and to phenanthrene3 has been described. It has now been found that certain acetylenes undergo photo-addition to benzene giving cyclo-octa-tetraenes.Irradiation of methyl propiolate (5.0 g.) in benzene (140 ml.) under nitrogen for 20 hr. at 53" in an apparatus previously described4 gave methyl cyclo-octatetraenecarboxylate(0.8 g.) having the correct infrared ~pectrum.~ The corresponding acid m.p. and mixed m.p. 72.5" (lit. 72.5") had ultra- violet and infrared spectra identical with those of material prepared by carboxylation of cyclo-octatetraenyl-lit hi~m.~ Similarly irradiation of dimethyl acetylenedicar- boxylate (4-0 g.) in benzene (150 ml.)under nitrogen for 20 hr. at 50-55" gave a yellow 1 :1 adduct (dimethyl cyclo-octatetraene- 1,2-dicarboxyIate) (2-0 g.) m.p. 109-5-110-5" (Found M 224.Cl2HI2O requires M 220) and the corresponding acid m.p. 207-5-208.5 " (decomp.) (Found Equiv. 95-5. C1,H,O requires equiv. :96-0) the latter with ultra- violet and infrared spectra similar to those of the monocarboxylic acid.5 The infrared spectra of the methyl esters were also quite similar. Catalytic hydrogenation (Adams catalyst) of the dicarboxylic acid in acetic acid (10 hr.) and ethanol (30 min.) led to the consumption of 4.0 and 3.95 mol. of hydrogen respectively. Only one subsequent attempt to repeat these results with different batches of catalyst proved successful and absorption of the fourth mol. of hydrogen was usually incomplete even after several days. Irradiation of phenylacetylene (7 6.) in benzene (130 ml.) for 18 hr.under nitrogen at 56-58' gave phenylcyclo-octatetraene (0-2 g.) having ultraviolet and infrared spectra almost identical with those of material prepared by Cope and Kinter's method.6 The photochemical product differed in its failure to form adducts with maleic anhydride or p-benzo- quinone. This result is under investigation but may indicate a difference in conformation and the minor spectral differences may prove significant. Traces of a blue oil l-phenylazulene were also obtained and were identified by the visible absorption maxima.' Acetylene itself appears not to add readily to benzene under the present conditions but irradia- tion at 52-56" of benzene in acetone which was Angus and Bryce-Smith Proc. Chem. SOC.,1959 326; J.1960,4791. Grovenstein Rao and Taylor J. Arner. Chem. Soc. 1961 83 1705. Bryce-Smith and Vickery Chem. and Znd. 1961,429. Blair Bryce-Smith and Pengilly J. 1959 3174. * Cope Burg and Fenton J. Amer. Chem. SOC.,1952,74 173. Cope and Kinter J. Amer. Chem. SOC.,1951,73 3424. 'Plattner Gordon and Zimmermann Helv. Chiin. Acta 1950 33 1910. kept saturated with acetylene gave a complex mixture in which the presence of a trace of cyclo- octatetraene was indicated by gas chromatography. Of course this could also have been formed by phototetramerisation. The formation of cyclo-octatetraenes by these reactions can be considered to involve initial 1,Zaddition of the acetylene as of maleic an-hydride.ls2s3 Whereas the initial 1 :1 benzene-maleic anhydride adduct undergoes 1,4-addition of a further molecule of anhydride the corresponding adducts of acetylenes undergo ring opening to give cyclo- octatetraenes which are fairly unreactive towards most dienophiles under the conditions employed.PROCEEDINGS Grovenstein and Raos recently described the photo-adduct of dimethyl acetylenedicarboxylate and benzene which they also formulate as dimethyl cyclo-octatetraenedicarboxylate on the basis of its spectra and the absorption of 3.6 mol. of hydrogen on catalytic hydrogenation of the derived acid. The question whether the original acetylenic bond appears specifically as a double or a single bond in the final product is under investigation. One of us (J.E.L.) thanks Esso Research Ltd.for a maintenance grant and for laboratory facilities. (Received July 7th 1961.) * Grovenstein and Rao Te?ralzedronLetters 1961 No. 4 148. The Preparation and Rearrangement of (+)-1-Phenylallyl Chloride By E. S. WAIGHTand M. WEINSTOCK (IMPERIALCOLLEGE S.W.7) LONDON THErecent observations of Winstein and his co- workers1 on the relative ease of racemisation ex- change and solvolysis of optically active halides prompted us to examine the properties of optically active 1 -phenylallyl chloride. (-)-1 -Phenylallyl alcohol -9.05"(liquid) was prepared through the quinidine salt of its hydrogen phthalate;2 on reaction with thionyl chloride in chloroform in the presence of triethylamine3 it gave (+)-1-phenylallyl chloride + 14.85" (incyclohexane) containing less than 3 % of cinnamyl chloride.The ally1 chloride racemised completely in NN-dimethylformamide at 40.0" (krac 0.00046 min.-l) somewhat faster than it isomerised to cinnamyl chloride (ki 0.00040 min.-l). In this solvent the rates of racemisation and rearrangement3 both increase linearly with the con- centration of added lithium chloride so that k[;$] = krac + a[LiCl] and k[sT1tl= ki + b[LiCl] where a and b have the units of second-order rate constants. At 40.0" a is 0.013 1. mole-l min.-l and b is -0.0024 1. mole-l min.-l. Racemisation is complete in ethanol or 90% aqueous dioxan. As shown in the Table krac is larger than the total rate constant (kt = ks + kj) for solvolysis (ks) and isomeric rearrangement (ki) in both media so that kraC -kt gives the rate of forma- tion of racemic l-phenylallyl chloride.(krac -kt)/ki compares the loss of configuration at the 1-carbon atom with rearrangement to cinnamyl chloride and has values of 0.58 and 0.68 at 30.0" for ethanol and 90 % aqueous dioxan respectively. In dimethyl-formamide this ratio is 0.15. The detailed mechanistic interpretation of these results must await examination of isotopic exchange reactions; however the following observations may be made First addition of lithium chloride pro- motes formation of racemic 1-phenylallyl chloride more strongly than isomerisation to cinnamyl chloride. Secondly if in the absence of salt the racemisation-rearrangement involves an intermedi- ate1%4 which returns to 1-phenylallyl chloride more Rate constants (min.-l) for racenlisa tion soEvoIysis and isonieric rearrangement (at 30.0").102krac 102ks I02ki Ethanol 6.62 4.00 1-66 90% Dioxan-H,O 1-39 0.35 0.62 rapidly than it forms cinnamyl chloride then it does so more often than not to produce the original structure. Nevertheless the observed values of (krac -kt)/ki indicate that such an intermediate is more likely to lose configuration in strongly ionising media such as ethanol or aqueous dioxan than in dimethylformamide. We thank the Department of Scientific and Industrial Research for a Maintenance Award (to M.W.). (Received June 20th 1961.) Winstein Gall Hojo and Smith J. Amer. Chem. SOC.,1960 82 1010; Winstein Hojo and Smith Tetralzedrorz Letters 1960 22 12.Duveen and Kenyon J. 1939 1697; Goering and Dilgren J. Amer. Chem. SOC.,1959,81 2556. Valkanas and Waight J. 1959 2720. Pocker Trans. Faraday SOC.,1959,55 1266; Proc. Chem. SOC.,1961 140. SEPTEMBER 1961 335 Infrared-active Metal-Chlorine Stretching Frequencies By D. M. ADAMS (AKERS LABORATORIES WELWYN, RESEARCH THE FRYTHE HERTS) CHARACTERISTIC modes of many of the bonds in inorganic compounds occur at frequencies too low to be investigated by spectrometers with sodium chloride or potassium bromide prisms and only recently has it been technically possible to obtain the equivalent information from Raman spectral of coloured compounds. Much information about bonding in inorganic complexes is therefore lost.In order to obtain some basic data about metal-halogen stretching frequencies we have investigated the spectra of some complex halides in the 20-50 p region. These compounds were chosen since there can be little doubt about the assignment of the higher frequency bands observed thus giving a clear indication of the positions of vM-CI for the heavier transition metal-chlorine bonds. In nearly all of them the expected infrared-active VM-CI frequencies are degenerate. Since all the spectra were examined as solids (Nujol mulls) it was expected that these bands would be broad because of partial removal of this degeneracy in the crystal. Further splitting due to vM-CI 37 is also possible since the isotope abund- ance of chlorine-37 (246%) is high enough to make a significant contribution.Our spectrometer has sufficient resolution to resolve this splitting. The bands observed are given in the Table. Some showed indications of more splitting than is listed but unless a band maximum was resolved it was not included. Further study of these splittings is neces- sary to elucidate them fully. Palladous chloride is known to be arranged in the solid as an infinite chain involving chlorine bridging.2 The same struc- ture is likely for PtCl,. We find that vpt-C1 in this compound is lower than in either K,PtCl or K,PtCl, as would be expected for a bridging group. Injiared active metal-chlorine stretching frequencies (cm.-l). K,ReCl, 331*5vs 319vs K,PdCl, 357.6~~ K20sC1, 340vs 3 19vs K2PtC14 328sh 320.5~~ K21rC16 342vs 332sh PtCI2 3 13vS K2PtCl 345vs The third-row transition elements show a steady rise in VM-CI from Re to Pt whilst a rise in UM-C~is found from Ptto Pd.These tendencies parallel closely the changes in VM-F found for a series of octahedral fluorides by Peacock and Sharp.3 All spectra were recorded at room temperature in a far-infrared vacuum spectrometer designed and constructed in these laboratories and which will be described elsewhere. I thank Mr. N. Palladino for experimental assistance. (Received July 17th 196 I .) Woodward and Creighton Spectrochim. Acfa 1961 17 594. Wells 2.Krist. 1939 100 189. Peacock and Sharp J. 1959 2762. Perchlorate Co-ordination in Metal Complexes By N.T. BARKER and E. D. MCKENZIE C. M. HARRIS OF INORGANIC THEUNIVERSITY (DEPARTMENT CHEMISTRY OF NEWSOUTHWALES BROADWAY AUSTRALIA) SYDNEY CONDUCTOMETRIC measurements show that bis-2,2'- bipyridylcopper(u) perchlorate behaves as a weak electrolyte in nitrobenzene while the corresponding hexafluorophosphate and the trischelated complex [Cu(bipy),(ClO,),] behave as strong electrolytes. The weak electrolyte behaviour of Cu(bipy),(ClO,) is due to the equilibrium [Cu(bipy),(ClO,)]+ + Ph-NO + [Cu(bipy),(Ph.N0&I2++ C10,-and the conductometric data give a value of lo3 for the stability constant of the perchlorato-bi~-2,2'-bipyridylcopper(11)ion at 25". The analogous 1,lO-phenanthroline complex Cu(phen),(ClO,) behaves similarly. The five-co-ordinated species [Cu(chel),(ClO,)]+ (chel = phen or bipy) have been isolated as the hexafluorophosphates [Cu(chel),(C1O,)]PFG and their formation is similar to that recently reported for the more stable five-co- ordinated [Cu(chel),X]+ complexes (X = C1 Br I SCN NO2 RC02).l Confirmation that perchlorate co-ordination and not simple ion-pairing is involved is shown by the effect of additional perchlorate ions on the visible Harris Lockyer and Waterman Nature 1961 in the press; Barclay and Kennard ibid.1961 in the press. absorption spectrum of [Cu(bipy),](PF,) in an- hydrous nitrobenzene. Its broad absorption band (Amax = 660 mp) is shifted to longer wavelengths (A,, = 700 mp) and from the spectral data the stability constant is calculated to be 3 x lo3.Also the spectra of solid [Cu(bipy),(C10,)]C104 and solid [cu(bipy),(ClO,)]PF in the 400-800 mp region are virtually identical (Amax = 670 mp). The spectrum of the four-co-ordinated compound C~(bipy),(PF,)~ is however different [A,, = (415) 590 700 mp]. Differences between the spectra of solutions and of PROCEEDINGS the solid are probably due to solvation effects causing differences in stereochemistry. This phenomenon has also been observed by us in other copper(rr) complexes such as [Cu(2-C,H4N-CH NCH,),(C104)]C104 and in the anhydrous paramagnetic (p = 3-2 B.M.) complexes Ni(chel),(CIO,),. The diamagnetic nickel(@ compound3 N~[o-C,H,(ASM~~,]~(C~OJ~ also forms in nitrobenzene solution a perchlorato-complex which has been isolated as the compound [Ni(o-C,H,(AsMeJ ),C10,] PF,? (Received May 30th 1961.) a Harris and McKenzie J.Inorg. Ntdear Chem. 1961 in the press a Harris Nyholm and Phillips? J. 1960,4379. Harris and Lockyer unpublished observations. The Stability Constants of Some Complexes of the Early Cations of the First Transition Series By J. M. CRABTREE R. J. P. WILLIAMS, D. W. MARSH,J. C. TOMKINSON and W. C. FERNELIUS (CHEMISTRY PENNSYLVANIA COLLEGE, DEPARTMENT STATE USA.,and INORGANIC LABORATORY OXFORD) CHEMISTRY THE UNIVERSITY IN Table 1 we collect some stability constants of chromous and vanadous complexes mostly ob- tained by us by the methods described for cuprous and ferrous comp1exes.l The constants demonstrate the following points (1) The stability sequence for the high-spin states of bivalent ions of the first part of the transition to the small size and strong nacceptor properties of the first cations in a transition series.3 This group of ligands binds later cations of the transition series e.g.Cu(Ir) with approximately the same strength as it binds V(II). (3) Unsaturated amines e.g. bipyridyl form stronger complexes than saturated amines e.g. TABLE 1. Logarithms of step stability constants of vanadium and chromium complexes. EDTALigand 1274 Kl V(U) K2 - K3 - Oxalate 2.5-3'0 - - Salicylate 6.27 4.7 1 - Acetylacetonate Oxinate 8.58 12-7a 7.14 10-86 - Ethylenediamine 2,2'-Bipyridy l 4-63 4-91 2-95 4-67 1-33 3.85 * Aq.D = 50% v/v Aq. dioxan.series i.f.,from Ca(Ir) to Mn(Ir) is ligand-dependent. Some sequences are given in Table 2.The stability sequences found in the second part of the transition series from Mn(I1) to Zn(n) do not show a similar ligand-dependence.2 (2) Ligands containing RO- e.g. hydroxide enolates and phenoxides form particularly stable complexes with the cations V(II) and Cr(II) as com- pared with Ca(I1) and Mn(r1). We take this to be due Wn) k-1 K2 K3 8*465 6~95~ -5-15 4.046 V.S. 4 -6.4 3.5 ethylenediamine. A comparison between N i(n) log 16 (en) = 18.5 log (bipy) = 20.0 and V(II) (see Table 1) shows that r-donor properties are more important in the fist part of the transition series although all nitrogen donors are more strongly bound by the second part of the series.This is expected from the increase in polarising power with atomic number. (4) A change of spin state occurs on the addition 1 Tomkinson and Williams J. 1958 2010; James and Williams J. 1961 2007. Irving and Williams J. 1953 3192. a Williams J. 1956 8; Discuss. Faraday SOC.,1958 26 123. 4 Schwarzenbach and Sandera Helv. Chim. Acta 1953,36 1089. 6 Pecsok and Schaefer J. Amer. Chem. Soc. 1961 83 62. Pecsok and Bjerrum Acta Chem. Scand. 1957 11 1419. SEPTEMBER 1961 of the second bipyridyl molecule to the chromous ion. We have proved this by a measurement of the magnetic susceptibility of [Cr(bipy),(H20),j(C10,),. The sample was kindly supplied by Dr. G. M. Waind and Mr. R. Murray Queen Mary College London.Thus the change of spin state of the d4-ion is more easily achieved than that of the d6-ion Fe(11). This is of oxalate and EDTA complexes may well be due to the small size of the ions but the high stability of RO-and unsaturated-amine complexes must be related to the energy of the 3d-electrons. Be this as it may it is clear that a given ligand cannot be repre-sented by a field parameter A which is independent of the cation concerned throughout the transition TABLE 2. Ligand Stability constant Oxalate Ethy lenediamine-’ te tra-acetate Ethylenediamine Salicylate 1% B1 log P2 Bipyridy1 log B1 log P3 contrary to the predictions of crystal-field theory.’ After the change of spin state the chromous-bi- pyridyl complexes are more stable than those of vanadous.From a consideration of all four points we conclude that n-bonding has a considerable influence on the stability of complex ions in the first part of the transition series and that this influence is greater than in the second part. The cations in the first part of the series are smaller as measured in oxides and their 3d-orbitals are more diffuse. The low stability Sequence Ca(ir) < V(II) < Mn(ri) Ca(r1) < V(n) < Cr(I1) > Mn(1r) Ca(i1) < V(n) > Cr(n) > Mn(u) Ca(1r) < V(n) 3 Mn(I1) series. Such an assumption has been frequently used in discussions of the stability of complex ions.’ Measurements on tervalent cation complexes indicate that the stability sequence is often Sc(nr) < Cr(r11) < Fe(II1).There is as yet no evidence for higher stability of chromic than of ferric complexes. This work was supported by AEC contract AT (30-1)-907. J.M.C. thanks the U.K. Atomic Energy Authority for a bursary. (Received July 3rd 1961 .) Orgel “An Introduction to Transition-Metal Chemistry,” Methuen London 1960 pp. 45-50 70-75. Surface PhotoIysis Experiments on Evaporated Metal Films By P. WHITE CENTER HEIGHTS, (IBM RESEARCH P.O. Box 218 YORKTOWN NEWYORK,U.S.A.) IT has been shown by Harris and Willard1 that the photo-activated exchange between methyl iodide and iodine could be best explained by a mechanism in which photolysis of methyl iodide in an adsorbed layer on the glass surface of the containing vessel was an important step.In examining the photolysis of methyl iodide and methyl bromide in the presence of various metals McTigue and Buchanan2 concluded that one of the initial steps was the photodecomposi- tion of the methyl compound in an adsorbed layer. Induced decomposition of adsorbed gases other than methyl compounds has also been observed. It is thought for example that the contamination found on the anode in electron-diffraction cameras is due to the formation of a solid polymer by surface poly- merisation of silicone pump-oil vapour present in the system. The formation of solid polymer by this means has in fact been investigated by Buck and Shoulders3 and by Christy,” who showed that surface polymerisation is highly selective it occurs only on those parts of the surface exposed to the electron beam.When the whole area of a freshly prepared lead or tin filmexposed to methyl iodide or methyl bromide was illuminated with ultraviolet light the whole of the film was removed. Undoubtedly this was due to the formation of the volatile metal-tetramethyl com- pound. When by use of a mask only part of the Harris and Willard J. Amer. Chem. Soc. 1954 76,4678. McTigue and Buchanan Trans. Furuduy SOC.,1959,55 153. Buck and Shoulders Proc. Eastern Joint Computer Conference Philadelphia 1958. Christy J. Appl. Phys. 1960 31 1680. PROCEEDINGS metal film was exposed to the light only the illumi- the mechanism in which selective photolysis of nated area was removed.If butadiene was used in adsorbed gas occurs. place of the methyl compound a polymer film was Surface diffusion of the active species is not con- formed selectively on the illuminated area only. By sidered to be a major factor since a section of a the controlled projection of an image therefore a metal surface 0.005inch wide can be left compIetely definite pattern may be etched from a lead or tin uncovered with polymer if it is not illuminated. The film (or presumably any other metal which forms a rate of the etching process is markedly dependent on volatile methyl compound) or a definite pattern of the amount of oxide present on the metal surface polymer film may be formed. but does not change much from tin to lead. The rate These experiinents indicate either a surface of formation of the polymer film depends on the photolysis in which decomposition occurs in the nature of the underlying metal film and in each case adsorbed layer or that free radicals formed in the decreases with increasing temperature.Both pro- gas phase react preferentially on the illuminated cesses seem to be relatively insensitive to gas pres- areas. When a metal film containing an adsorbed sure variations from 0-5 to 10 cm. producing no layer of methyl iodide was exposed to ultraviolet noticeable change in the rate of etching or of poly- light at lo- mm. the illuminated metal surface was merisation. Apparently the only requirement is that attacked slightly in the first minute or so with no the pressure is sufficient to maintain an adsorbed further reaction on continued exposure.This favours layer on the metal surface. (Received June 12th 1961.) The Abstraction of Chlorine Atoms from Gaseous t-Butyl Hypochlorite by Methyl Radicals By L. PHILLIPS RESEARCH MINISTRY (EXPLOSIVES AND DEVELOPMENT ESTABLISHMENT OF AVIATION WALTHAM ESSEX) ABBEY THE only published data on the vapour-phase hypochlorite to form methyl chloride. A similar pyrolysis of t-butyl hypochlorite are those of Yoffe,l suggestion has recently been made by Walling and who used a flow method at 340" with helium as Jacknow, who showed that cyanoisopropyl radicals carrier gas. Complete decomposition occurred and methyl radicals abstract chlorine atoms from mainly to acetone and methyl chloride and the chief t-butyl hypochlorite in the liquid at 40".Abstraction reactions were written as of halogen atoms from alkyl halides by methyl radicals in the vapour has also recently been Me,COCl -f Me,CO. + C1. . . . . . (1) Me,CO--+ Me- + Me,CO . . . . . (2) demonstrated by Evans Fox and Szwarc.* This hypothesis can readily be tested by heating Me. + C1. -+ MeCl . . . . . . . (3) gaseous mixtures of di-t-butyl peroxide and t-butyl The nature of the products has now been confirmed hypochlorite at 100" in the dark. The hypochlorite at 160" and the initial 0-Cl bond fission established itself undergoes about 1% decomposition in 30 by decomposing the hypochlorite in the presence of minutes and the peroxide from the results of Raley nitric oxide large yields of t-butyl nitrite being ob- et aZ,,5 about 0.1 % decomposition mainly into tained.Reaction (3) as the main source of methyl methyl radicals and acetone. In a mixture of 13.7 chloride however appears to be unlikely because of mm. of t-butyl hypochlorite and 2.5 111111. of di-t-the small concentrations of methyl radicals and butyl peroxide at loo" complete decomposition of chlorine atoms in the system. the hypochlorite occurred in 30 minutes giving Abstraction of nitric oxide from alkyl nitrites by 13.2 mm. of methyl chloride and 12.9 mm. of methyl radicals in the vapour,2B6 suggested that a acetone plus a small amount of t-butyl alcohol. No similar mechanism might operate here i.e. methyl detectable reaction occurred in 30 minutes in the radicals might abstract chlorine atoms from t-butyl dark at room temperature.Yoffe Chem. and Ind. 1954,963. Jest and Phillim Proc. Chem. Suc. 1960 Feb. 73. Walling and Jacknow J Amer. Chem. Soc. 1960 82 6108. Evans Fox and Szwarc J. Amer. Chem. SOC.,1960 82 6414. Raley Rust and Vaughan J. Amer. Chem. SOC.,1948 70 88. Phillips Proc. Chem. Soc. 1961 204. SEPTEMBER 1961 These results indicate that the following long-chain mechanism is operative Me,CO,-CMe -+ 2Me,CO. Me,CO.+ Me-+ Me2C0 . . . . . (2) Me. + Me,COCl -+MeCl + Me,CO. (OW-36 kcal./mole) . . . . (4) Me,CO.-+ Me. + Me2C0 . . . . . (2) Me. + Me,COCI -+MeCl + Me,CO* etc. (4) 2Me. -+C2H6 . . . . . . . . . (5) In the pyrolysis of t-butyl hypochlorite alone the extra chain-termination step Me-+ C1. -+ MeCl . .. . . . . (3) limits the extent of decomposition. It is of interest to compare the above with the vapour-phase reaction of methyl radicals with t-butyl nitrite. Nitric oxide abstraction Me. + Me,CO*NO -+ MeNO + Me,CO-(6) established for other alkyl nitrites2s6 applies here so that a similar long-chain mechanism consequent upon the regeneration of methyl radicals from the t-butoxyl radical (reaction 2) might be expected. However only about 35% decomposition of the nitrite occurs in a mixture of 116 mm. of t-butyl nitrite and 105 mm. of di-t-butyl peroxide during 30 minutes at 160" (during which time about 70% of the latter decomposes). This is due to the breaking of the chain process by the ready addition of methyl radicals to the initially formed nitrosomethane to form trimethylhydroxylamine,6which is a product of the reaction.(Received July 20th 1961.) The Catalytic Action of Anionic Catalysts By ALWYN G. EVANS and E. D. OWEN J. C. EVANS DEPARTMENT COLLEGE, (CHEMISTRY UNIVERSITY CARDIFF) WHENa benzene solution of butyl-lithium is added to a benzene solution of 1,l-diphenylethylene a coloured solution is obtained having the spectrum shown in curve A.l We have attributed this spectrum to the carbanion of the ion pair Bu.CH,CPh,-Li+. However when the linear dimer of the olefin namely 1,1,3,3-tetraphenyIbut-l-ene,is used no We have now added a tetrahydrofuran solution of sodium naphthalene to a tetrahydrofuran solution of 1,1,3,3-tetraphenylbut-l -ene. The green colour of the sodium naphthalene solution2 changed immedi- ately to led.A concentrated solution showed an absorption peak between 345and 590 mp; at higher wavelengths of the visible region there was no Wqvelength (my) Curve A. Benzene solution of LiBu (1.51 x mole l.-l) and CH,:CPh (1.01 x mole l.-I). Curve B. Solution obtained by adding 6.2 ml. of sodium naphthalene solution (2.2 x mole l.-l) to 6.4 ml. of CH,-CPh,CH :CPh solution (6.05 x lo-* mole l.-l). Spectrum measured 10 minutes after mixing. colour is obtained. This is due we believe to the fact that the butyl ion cannot add to the linear dimer to form the anion CH,CPh2CHBuCPh2- because of steric hindrance between the phenyl groups and the butyl gr0up.l absorption. This solution did not fade but the colour was too intense for the optical density at the peak wavelength to be measured so a much more dilute system was made up adding 6.2 ml.of sodium naphthalene solution (2-2 x mole L-l estimated Evans and George Proc. Chern. Suc. 1960 144; Evans and George in the press. Paul Lipkin and Weissman J. Arner. Chem. SOC.,1956 78 116. spectroscopically) to 6-4 ml. of a 1 ,1,3,3-tetraphenyl-but-1-ene solution (6.05 x mole I.-l). A red solution was obtained the intensity of which de- aeased with time; the spectrum measured 10 minutes after mixing is shown in curve B. It is seen that this spectrum has practically the same peak wavelength as that for Bu.CH,-CPh,-Li+. On the long-wavelength side of the peak the absorption PROCEEDINGS falls to zero at 590 mp.On the short-wavelength side there is an increase in absorption below 370 mp; this however is due to the naphthalene in the solution. These results show that although it is sterically impossible to add a bury1 anion to the double bond of 1,ly3,3-tetraphenylbut-l-ene, it is possible to add an electron to this olefin. (Received June 29th 1961 .) An Application of High-speed Digital Computers to the Calculation of Formation Constants for Tervalent-metal Complexes By W. J. RANDALL and T. MOELLER D. F. MARTIN (NOYES LABORATORY OF ILLINOIS ILL. U.S.A.) CHEMICAL UNIVERSITY URBANA RECENTdiscussions1s2 of the application of high- speed digital computers to the calculation of formation constants of complex species have re- viewed the technique of calculation’ and summarised results from solvent-extraction data.2 We have adapted the ligand-number method of Bjerrum3 to systems involving bidentate chelating agents where three such ligands (N = 3) may be gramme.For each volume of added alkali after which the pH-meter reading was measured the re- sulting programme yields n the ratio of the concen- tration of complexed ligand to the concentration of all metal-ion species in solution and fn,which is defined as fn = (n -FI)[C~-]’~ where [Ch-] is the concentration of free chelate Comparison of manually and programme-calculated values of formation constants of’ 4-p-nitrophenyliminopentan-Zonechelutes at 30.0” & 0.05 O Tervalent-metal ion La Ca 3 1% Kl 10.57 f0*16b log K2 8.80 f0.15 48 10.83 & 0.07 8-79 f0-01 Srn 4 10.81 i0.11 9-11 f0.06 80 10.78 f0.01 9-11 5 0-01 Gd 3 11.14 &-0.09 9.14 f0.17 72 11-14 f0.01 9-13 i0.01 DY 3 60 11-12 k0-03 11.12 f0.01 9-10 i0.23 9.10 -+ 0.01 Er 3 11.10 f0.05 9-03 0.02 96 11-08 f0.00 9-06 & 0.00 Yb 3 11-33 f0.10 9-39 -l0.24 40 11-33 f0-01 9.37 -l0.01 a Total no.of combinations of n’ 2,and T’* used (i.e. degrees of freedom log K3 Method 7-10 f0.14 Manual 7-13 0.01 Programme 7.21 & 0-02 Manual 7.22 f0-00 Programme 7.42 0-10 Manual 7.42 f0.00 Pro gramme 7.39 f0.10 Manual 7.38 f0.01 Programme 7-46 &-0.05 Manual 7.46 f0.00 Programme 7.76 f0.03 Manual 7.79 -+ 0.00 Programme = C-1).95% confidence limits. bonded to a given metal ion.4 Specifically the pro- gramme for the computer has been devised to evaluate successive formation constants (expressed as log Ki) for ,&diketone and p-keto-imine chelates of tervalent cations from potentiometric-titration data obtained in a dioxan-water ~ystem.~ Equations previously reported4 for the case N = 3 have been used in preparing the computer pro- anion. Both the total volumes of alkali solution added and the corresponding ii values are printed. The latter are then divided into three ranges -~=0.30-0-70;h’= 1.30- 1-70;n* =2-30-2-70; and data for values not in these ranges are rejected. All possible combinations of acceptable Z E’ and E* values being used log Ki values and their respective means and variances are printed.Sullivan Rydberg and Miller Acta Chem. Scand. 1959 13 2023. a Rydberg Acta Cliem. Scand. 1960 14 157. Bjerrum “Metal Ammine Formation in Aqueous Solution,” P. Haase and Son Copenhagen 1941. Block and McIntyre J. Amer. Chem. SOC.,1953 75 5667. Van Uitert and Fernelius J. Amer. Chem. SOC.,1954 76 5887. SEPTEMBER 1961 Calculations involving all possible combinations of E Z’ and T’* are essential to evaluation of the most reliable Kivalue for any one titration. A single manual calculation of this type requires 1-2 hours and is subject to human error and prejudice. The same calculation made by the digital computer according to the above programme requires -2 seconds and each set of titration data can be pro- cessed in 5-10 minutes.The time required to prepare a set of data for computer treatment is -30 minutes. An indication of the applicability of this approach is the excellence of agreement between manually calculated6 and computer-calculated values of log Ki for 4-p-nitrophenyliminopentan-Zone complexes of selected tervalent rare-earth metal ions shown in the Table. 341 It should be pointed out that formation constants have been reported on the basis of as few as two or three and commonly not more than seven com- binations of Z Z’ and Z*. Such a statistically unsound practice is eliminated in the approach described since all acceptable Ti values are used and weighted equivalently.Detailed descriptions of the programme are available upon request. The authors thank Mrs. G. Belford for assist- ance with the preparation of the computer pro- gramme and Dr. w. C. Fernelius for herpful suggestions. This investigation was supported in part by PHS Research Grant 7873 Division of General Medical Sciences U.S. Public Health service. (Received June 26th 1961 .) Janusonis Bachelor’s Dissertation University of Illinois 1960. The Transition State in Nucleophilic Aromatic Substitution By J. R. KNOWLFS,R. 0. C. NORMAN, and (Miss) J. H. PROSSER (DYSON LABORATORY OXFORD) FERRINS THEUNIVERSITY THE transition state of an aromatic substitution in which the first step is rate-determining has been assumed to have a structure intermediate between those of the isolated reactants and the Wheland a-comp1ex.l We report here results which give information about (a) the nature of the transition state in the nucleophilic displacement of chloride ion (in aromatic chloronitro-compounds) by phen- oxide ion and (b) the effect of change in reactivity Subst.H p-Me rn-OMe 10k (2,4-DN) 1-62 3.43 1.19 10% (1,4DC) 2.45 5.03 1.66 of the chloronitro-compound on the structure of this transition state. We have studied the reactions of meta-and par-substituted phenoxide ions with l-chloro-2,4-dinitro- benzene (2,4-DN) and with 1,4-dichloro-2-nitro-benzene (1,4-DC) in 80% dioxan-water at 65O.* The second-order rate constants (1. mole-l sec.-l) (Table) were obtained from measurement of the rate of appearance of displaced chloride ion.For both compounds the rate constants for dis-placement vary markedly with change in the sub-stituent in the phenoxide ion. More specifically the Hammett p-value obtained by plotting log (k/k,)for the nucleophilic displacement of 1-chloro-2,4-di-nitrobenzene against the a-values3 of the sub-stituents in the phenoxide ion is about -1.8. This large value is comparable with those derived from the protonation of phenoxide ions? Since in the p-Cl rn-C1 m-NO p-NO, 0.956 0-446 0.177 0.00845 149 0.735 -latter process the phenoxide ion loses its negative charge completely we conclude that in the transition state for displacement with 1 -chloro-2,4-dinitro- benzene a large proportion of the charge on the phenoxide ion has been transferred to chlorodinitro- benzene.Further the point corresponding to the p-nitro-group lies on the best straight line only when the U-value assumed for it is that appropriate to the ionisation of phenols (1~27),~ which indicates that * For reactions of 1,4-dichloro-2-nitrobenzene it was assumed that the chlorine ortho to the nitro-group was displaced since it is known that this is about 50 times as reactive as the chlorine meta to the nitro-group in nucleophilic substitu-. tions.2 de la Mare and Ridd “Aromatic Substitution,” Butterworths Scientific Publ. London 1959 p. 224. 2Todd and Shriner J. Amer. Chem. SOC.,1934 56 1382. Hammett “Physical Organic Chemistry,” McGraw-Hill Book Co. Inc. New York 1940 p.188. Jaffk Chem. Rev. 1953,53 191. 342 PROCEEDINGS there is a large change in the resonance interaction between the functional centre and the substituent in the phenoxide ion in passage from the ground state to the transition state of the displacement? These Ar-0'-GN02Ar-q"02 NO (1) NO2 (u) facts are consistent with the phenoxide ion's having become appreciably bonded to dinitrochlorobenzene at the transition state (I) which therefore closely resembles the Wheland a-complex (11). The second significant feature of the results is that a plot of log (k/k,)for the reactions of l-chloro-2,4- dinitrobenzene against log (klk,) for the reactions of 1,4-dichlor0-2-nitrobenzeneis linear with a slope very close to unity (gradient 0.94; correlation coefficient,0.998 ;standard deviation 0.07">.That is the p-values for these reactions are the same within experimental error even though the reactivities of the compounds towards a given phenoxide ion differ by a factor of more than 1oQ. The identity of the p-values shows that the structure of the transition state does not alter significantly with change in the substituent on the electrophilic species despite the large difference in reactivity caused by this change. van Bekkum Verkade and Wepster Rec. Trav. chim 1959 78 815. (Received July loth 1961.) Partial Resolution of the Rotational Structure of a Bending Vibration of Thiocyanic Acid in Solution By N. LEGGEand A. D. E. PULLXN OF CHEMISTRY UNIVERSITY (DEPARTMENT THEQUEEN'S OF BELFAST) IN an investigation of the spectrum of thiocyanic acid (HNCS) in a variety of solvents we observed a broad absorption band centred at 600 cm.-l having considerable structure which we believe is due to rotational motion of HNCS in solution.Reid1 examined the vapour-phase spectrum of HNCS and tentatively assigned a similarly broad band centred at 600cm.-l to the out-of-plane bending mode with irregular perpendicular rotational structure. In the Figure we compare the band observed by us in solu- tion in cyclohexane and in carbon disulphide with that observed by Reid. To make sure that the broad- ness in solution was not due to association solutions of concentration -0.15~to -0.003~in carbon disulphide were examined.A five-fold scale expan- sion was used for the weaker solutions; cell thick- nesses were 0.5 and 2.0 m.The great width of the absorption band remained unchanged on dilution; even at the highest dilution used some of its structure could still be clearly discerned though then because of the difficulty of exact compensation when the solute absorption is relatively weak some details became uncertain. The lack of observed concentra- tion-dependence indicates that the broadness of the band is not due to association cryoscopic measure- ments (in cyclohexane) also showed that at these concentrations association was small. Reliable spectra over most of the band region were obtained with cyclohexane decalin squalane and carbon disulphide. The long-wavelength side of the band was examined for carbon tetrachloride solu- Reid J.Chern. Phys. 1950 18 1512. tions. The structure was best resolved in cyclohexane and decalin; squalane was inferior in this respect to carbon disulphide. The Table gives the frequencies in cm.-l of the submaxima or shoulders obtained from an examination of a considerable number of spectra in which special attention was given to the 0 I 1 I 1 L 800 600 400 Frequency (cmi) Comparison of the 600 cm.-l band of HNCS in solution and in the vapour phase. A Solution in cyclohexane -0.02 M 1.0 mm. cells. B Solution in CS2 -0.025~,1-0 cells. C Vapour path-length pressure product in cm2=20. [The curve for the vapour is reproduced by permis-sion of the American Institute of Physics from the Journal of Chemical Physics (ref.l).] SEPTEMBER 1961 elimination of effects due to inadequate compensa- tion or atmospheric absorption. The 600 cm.-l band has the same general shape in carbon tetrachloride but adequate compensation for the very strong solvent absorption on the high-frequency side was not possible. Well-resolved rotational structure has been observed in the Raman spectrum of liquid hydrogen2 and in the infrared spectra of watera and ammonia4 trapped in matrices of solid inert gases. Wavenumbers (cm.-f) of shoulders and submaxima for HNCS in the solvents stated. Cyclohexane Decalin CS2 795a -795" 752b 754 745 690 690 690 638 641 -a 598 -a 597 465 465 465 a Obscured or made doubtful by solvent bands.'Broad. The band at 465 cm.-l belongs to a different mode. In solution a variety of simple molecules give spectra5 which strongly suggest smoothed-out P,Q and R branches even for molecules which do not show a Q branch in the vapour-phase spectra. This Q branch or strong central maximum appears also in our spectra though less strongly than in the spectra previously rep~rted.~ From the Figure it can be seen that there may be some correspondence of detail between the gas-phase and the solution spectra. The former spectra have on the high-frequency side the appearance of a series of doublets whose centres are at separations of -46 -1 12 and -170cm.-l from the assumed band origin at 600 cm.-l while the solution-phase spectra have submaxima at separa- tions of -40 -98 and -156 cm.-l from the central maximum at 598 cm.-l these separations in solution are -0.9 of those for the gas phase.Thiocyanic acid HNCS is a highly prolate (i.e. spindle-shaped) slightly asymmetric top with an unusually large rotational constantG of 43.1 cm.? for rotation about the spindle axis. For a perpendi- cular band of such a molecule the overall scale of the band is controlled by the rotational constant about this axis the details of the complicated rotational structure of the band are due to the simultaneous changes in rotation about all three axes. If in solution rotation were restricted by the solvent to rotation about the spindle axis about which rotation might be expected to be much freer the general scale of the spectrum would remain the same but the spectrum should be the much simpler one of a fixed-axis rotor since only one moment of inertia would be involved.It is tentatively suggested that the similarity observed between the solution and the vapour-phase spectra indicates some rotation about all three axes in solu- tion since the rotational constant about the spindle axis is critically dependent on the HNC angle a small change of this rotational constant in solution' sufficient to explain the factor of 0.9 used above is not a difficuhy. In the gas phase the NH stretching mode of HNCS has a strong narrow parallel component and a weaker perpendicular component which consists of a well-resolved series of Q branches spread over -300 cm.-l.We did not however observe any corresponding structure to this band in solution. (Received June 20th 196I .) McLennon and McLeod Nature 1929 123 160; Trans. Roy. SOC.Canada 1928 111 22 413; 23 19. Catalan0 and Milligan J. Chem. Phys. 1959 30 45. 'Hexter and Milligan J. Chem. Phys. 1961,34 1009. Bulanin and Orlova Optics and Spectroscopy,1958,4 569; Lascombe Huong and Josien BUN.SOC.chirn. Frame 1959 1175; Jones and Sheppard Trans. Faraday SOC.,1960,56 625. Jones and Badger J. Chem. Phys. 1950 18 1511. ' Pullin Spectrochim. Acic 1958 13 131; 1960 16 13. Charge-transfer Bonds in Solids:Crystal Structure of Oxalyl Bromide By P. GROWand 0. HASSEL (CHEMISTRY THEUNIVERSITY NORWAY) DEPARTMENT BLINDERN-OSLO BONDSpresent in solids between molecules containing both electron-donating and electron-accepting atoms are of considerable interest.Such bonds between halogen and nitrogen are no doubt present1 in cyanuric chloride2 and almost certainly also in the Hassel Tidssk. Kjemi Bergvesen Met. 1961 3 60. Hoppe LennC,and Morando 2. Krist. 1957 108 321. bromide and iodide resulting in strictly planar arrangements represented diagrammatically as (A) and analogous bonds will probably be found in other crystals. The fact that the oxalyl halides form 1 :1 addition compounds based on charge-transfer PROCEEDINGS bonds between chlorine and ether-oxygen atoms’ led us to study the crystal structure of oxalyl halides; we here report results for the bromide.The crystals are monoclinic space group P2Jc with a = 6-18 b = 5-46,c = 7.80 .$ ,8 = 112” 24’. The unit cell contains two molecules which are p centrosymmetrical and at least very nearly planar. The structure is based on non-planar sheets in which each oxalyl bromide molecule is linked to four neighbours by charge-transfer bonds between oxygen and bromine of length 3.27 A. Of three electron-density maps obtained that for a projection along the b-axis is reproduced in the Figure. The angle C-Br.-O is 169”. The bond distance and bond angles within a particular molecule are C-Br 1-84 C=O 1-17 and C-C 1.56 A 0-C-Br 128” 18’ Br-C-C 108” 48’ and 0-C-C 122” 18’. As well as the charge-transfer bond distance Br-0 = 3-27 A a Br-0 distance of 3-63 A occurs within the sheets.The shortest distances observed between atoms belonging to neighbouring sheets are Br-0 3.90 Br-Br=3.90 and C-0 3-40A. We think that these findings show conclusively that charge-transfer bonds are mainly responsible for the cohesion within the sheets. The crystal structure of oxalyl chloride is now being investigated. The chloride has a higher m.p. and crystallises in the space group Pbca with four molecules in the unit cell. (Received June 30th 1961) NEWS AND ANNOUNCEMENTS University of London.-The title of Professor Emeritus has been conferred on the following Professor Sir Christopher Ingold F.R.S. Professor of Chemistry at University College since 1930; Professor W.H. Linnell Professor of Pharmaceutical Chemistry at the School of Pharmacy since 1944 and Dean of the School; and Professor D. M. Newitt F.R.S. Courtaulds Professor of Chemical Engineer- ing at the Imperial College of Science and Tech- nology since 1945. Election of New FeUows.-37 Candidates whose names were published in Proceedings for July have been elected to the Fellowship. Deaths.-We regret to announce the deaths of the following Mr. H. H. Hughes (17.3.61) formerly of the Grammar School Tottenham; Dr. A. Jacobus (27.2.61) Research Chemist with George Nelson Dale and Co. Ltd. Wanvick; Dr. W. S. Nathan (6.8.61) of British Petroleum Sunbury; Professor R F. Naylor (6.8.61) Professor of Chemistry The Royal College Nairobi; Professor M.W. Travet-s (25.8.61) Professor Emeritus of Physics University of Bristol; and Mr. J. Wilson (1.7.61) formerly Inspector of Schools Ministry of Education. British Association Granada Lectures.-The 196I series of three lectures organised by the British Association and sponsored by Granada TV Net-work on the theme of “Communication in the Modern World” will be held at the Guildhall London. On October 3rd Sir James Gray C.B.E. M.C. F.R.S. wiIl lecture on “The Language of Animals” ; on October 12th Professor Hermann Bondi F.R.S. will lecture on “Why Scientists Talk”; and on October 17th Sir John Wolfenden C.B.E. will lecture on “The Gap-and the Bridge”. A limited number of tickets have been made available for Fellows of the Chemical Society wishing to attend these Lectures.Application should be made as soon as possible to The British Associa- tion Granada Lectures Granada TV Network Golden Square London W.1. SEPTEMBER 196I 345 International Congresses etc-The Fifth Inter- national Pigment Cell Conference sponsored by the New York Academy of Sciences and at which 70 papers will be presented covering recent develop- ments in the field of pigment cell biology and related disciplines will be held on October ll-l4th 1961 in New York City. Enquiries should be addressed to Dr. Vernon Riley Sloan-Kettering Institute for Cancer Research New York 21 New York U.S.A. A Symposium on Some Aspects of Vacuum Science and Technology will be held at the Imperial College of Science and Technology London on January 5th 1962.Enquiries should be addressed to the Administration Assistant The Institute of Physics and The Physical Society 47 Belgrave Square London S.W.1. An International Symposium on the Organic Chemistry of Natural Products under the auspices of the International Union of Pure and Applied Chemistry and in connection with the Seventy-fifth Anniversary of the foundation of the SociCtC Chimique de Belgique is to be held in Brussels on June 12-15th 1962. Copies of the first circular can be obtained from the Secretariat of the International Symposium of Organic Chemistry c/o Federation des Industries Chimique de Belgique 32 rue Joseph IT Bruxelles 4. The Seventh International Conference on Co-ordination Chemistry will be held in Stockholm on June 25-29th 1962.Enquiries should be addressed to Professor Lars Gunnar Sillbn Department of Inorganic Chemistry Royal Institute of Technology Stockholm 70 Sweden. An International Symposium on the Physics and Chemistry of High Pressures sponsored by the Society of Chemical Industry the Institution of Chemical Engineers and the Institute of Physics and the Physical Society will be held in London on June 26-28th 1962. Enquiries should be addressed to Professor J. S. Rowlinson Department of Chemical Engineering and Chemical Technology Imperial College London S.W.7. The Third International Congress of Catalysis is to be held in Amsterdam from July 20-25th 1964 and not in 1961 as announced in Proceedings for June.1961. Personal.-Dr. H. 0. Askew has been elected Chairman of the New Zealand section of The Royal Institute of Chemistry. Dr. F. H. BanfieZd has been appointed Technical Director of the Board of C. Shippam Ltd. Mr. Gwyn Benson Assistant Vice-president of Shawinigan Chemicals Ltd. of Montreal has been appointed Secretary of the Company. Dr. W.P. Doyle and Dr. J. L. Holmes have been appointed Lecturers in Chemistry at the University of Edinburgh from October lst 1961. Dr. F. N. Fastier has been appointed Associate Professor in Pharmacology in the Medical School University of Otago. Dr. A. Fischer of the Chemistry Department University of Canterbury has left to undertake work on reaction mechanisms with Professor G.Hammond at the California Institute of Technology. Dr. R. Gaze has been appointed an Executive Director to the Board of the Cape As'oestos Co. Ltd. The Hancock Medal of the Institution of the Rubber Industry has been awarded to Mr. M. M. Hey wood. Dr. A. R. Katritzky Fellow of Churchill College Cambridge has been visiting the United States on a lecture tour during August and September. Dr. R. Lessing has relinquished his position as Managing Director of Hydronyl Limited and has been appointed Deputy Chairman. Dr. B. R. Penfold Senior Lecturer in Chemistry at the University of Canterbury has returned after two years in the United States on a National Academy of Sciences Fellowship. Mr. H. V.Potter has been elected into the Court of Assistants of the Worshipful Company of Horners.Dr. A. V. Robertson currently a Visiting Scientist of the National Institutes of Health Bethesda has been appointed to a Lectureship in Organic Chem- istry in the University of Sydney. Dr. F. J. C. Rossotti has been elected to a Fellow- ship and Tutorship in Chemistry at St. Edmund Hall Oxford and appointed to a University Denionstratorship in Inorganic Chemistry. Dr. D. W. A. Sharp was appointed Senior Lecturer in the Department of Chemistry Royal College of Science and Technology Glasgow from September 1st. PROCEEDINGS PROGRAMME OF MEETINGS* OCTOBER 1961 TO JANUARY 1962 * Reprints of this programme can be obtained from the General Secretary,The Chemical Society Burlington House London W.l.London Thursday October 19th 1961 at 7.30 p.m. The following papers will be presented “Stereochemical Control in Oxidative Cyclisation,” by F. M. Dean. “A New Group of Antibiotics,” by I. 0. Sutherland and W. D. Ollis. “Rotenoids and their Relatives,” by L. Crombie. To be held in the Rooms of the Society Burlington House W.1. (Abstracts of the papers can be obtained from the General Secretary.) Thursday November 2nd at 2 p.m. Symposium on “Electron-spin Resonance”. To be held at Queen Mary College. (A full programme is being circulated.) Thursday November 16th at 7.30 p.m. Centenary Lecture “Some Reactions of Free Radicals,” by Professor G. B. Kistiakowski. To be given in the Rooms of the Society Burlington House w.l.Thursday December 14th at 7.30 p.m. Liversidge Lecture “Stereospecific Polymerisation,” by Professor C. E. H. Bawn C.B.E. Ph.D. F.R.S. To be given in the Lecture Theatre The Royal Institution Albemarle Street W. 1. Thursday January 18th 1962 at 7.30 p.m. Meeting for the reading of original papers. To be held in the Rooms of the Society Burlington House w.l. Aberdeen (Joint Meetings with the Royal Institute of Chem- istry and the Society of Chemical Industry to be held at Marischal College unless otherwise stated.) Wednesday October ISth 1961 at 8 p.m. Lecture “Recent Advances in Gas Chromatography and its Application to Biochemistry,” by Dr. A. T. James. Thursday November 9th at 8 pm. Lecture “The Discovery of New Drugs,” by Dr.A. F. Crowther M.A. Friday December 8th at 8 p.m. Lecture “Inorganic Heterocycles,” by Dr. I?. L. Paddock B.A. Wednesday January JOth 1962 at 8 p.m. Lecturz “Precision Balances ; History Develop- ment and Techniques,” with the film “The Balance and its Use,” by Mr. A. 0. Brooks. To be given in the Chemistry Department The University. Aberystwyth (Joint Meetings with the University College of Wales Chemical Society unless otherwise stated to be held in the Edward Davies Chemical Labora- t ories.) Thursday October 26th 1961 at 5 p.m. Lecture “Some Applications of X-Ray Crystallo- graphy to Chemistry,” by Mr. H. M. Powell M.A. F.R.S. Thursday November 9th at 5 p.m. Lecture “The Anatomy of the Chemist,” by Dr.T. S. Stevens A.R.I.C. Tuesday November 14th at 5 p.m. Lecture “Nuclear Magnetic Resonance Spectro- scopy,” by Dr. R. E. Richards M.A. F.R.S. Joint Meeting with the Royal Institute of Chemistry. Thursday December 7th at 5 p.m. Lecture “Microcalorimetry and the Therinogencsis of Living Species,” by Dr. H. A. Skinner B.A. Thursday January 25th 1962 at 5 p.m. Lecture by Dr. W. E. Hamer. Birmingham (Joint Meetings with the University Chemical Society to be held in the Chemistry Department The University.) Friday October 20th 1961 at 4.30 p.m. Lecture “Physical Adsorption,” by Professor D. H. Everett M.B.E. D.Phil. F.R.T.C. Friday November loth at 4.30 p.m. Lecture “The Active Centres of Enzymes,” by Professor H.N. Rydon D.Sc. F.R.T.C. Friday December lst at 4.30 pm. Lecture “New Reactions in Dinitrogen Tetroxide,” by Professor C. C. Addison D.Sc. F.R.T.C. Bristol Thursday October 5th 1961 at 6.30 p.m. Lecture “The Scientific Background of the Wine Trade,” by Mr. R. W. Goswell. Joint Meeting with the Royal Institute of Chemistry and the Society of Chemical Industry to be held in the Department of Chemistry The University. Thursday October 12th at 6.30 p.m. Lecture “Solid-fuel Rocket Propulsion,” by Dr. G. Young. Joint Meeting with the Royal Institute of Chemistry and the Society of Chemical Industry to be held at British Cellophane Bridgwater. SEPTEMBER 1961 Thursday October 19th. Lecture “The Chemistry of Polyamides,” by Mr.A. H. Hill. Joint Meeting with the Royal Institute of Chemistry the Society of Chemical Industry and the Plastics Institute to be held in the College of Technology Gloucester. Thursday November 2nd at 6.30 p.m. Lecture “Some Studies in the Porphyrin Field,” by Professor G. W. Kenner Ph.D. Sc.D. Joint Meeting with the Royal Institute of Chemistry and the Society of Chemical Industry to be held in the Department of Chemistry The University. Friday November 24th. Annual Dinner and Dance. Joint Meeting with the Royal Institute of Chemistry and the Society of Chemical Industry to be held at Long Ashton Research Station. Thursday December 7th at 6.30 p.m. Lecture “Mining Smelting and Refining of Nickel,” by Dr. G. L. J. Bailey.Joint Meeting with the Royal Institute of Chemistry the Society of Chemical Industry and the Institute of Metals to be held in the Department of Chemistry The University. Thursday January 11 th 1962 at 6.30 p.m. Lecture “Forensic Chemistry,” by Dr. F. D. M. Hocking M.B. M.Sc. Joint Meeting with the Royal Institutc of Chemistry and the Society of Chemical Industry to be held in the Department of Chemistry The University. Cambridge (Meetings will be held in the University Chemical Laboratory.) Friday October 27th 1961 at 8.30 p.m. Lecture “The Chemistry of the Tannins,” by Professor R. D. Haworth D.Sc. F.R.S. Joint Meet- ing with the University Chemical Society. Monday October 30th at 5 p.m. Lecture “Some Aspects of Kinetics of Reactions in Solution,” by Dr.V. Gold. Friday November 3rd at 8.30 p.m. Lecture “Dielectric Absorption and Aspects of Molecular Behaviour,” by Dr. M. M. Davies M.Sc. Joint Meeting with the University Chemical Society. Tuesday November 7th. Lecture “Unimolecular Decomposition of Excited Molecules Formed by Methylene Addition Re-actions,” by Dr. H. M. Frey M.A. Monday November 13th at 5 p.m. Lecture “The Physical Chemistry of Ion-exchange Polymers,” by Dr. E. Glueckauf. Friday November 17th at 8.30 p.m. Official Meeting and Centenary Lecture “Some Reactions of Free Radicals,” by Professor G. B. Kistiakowski. Joint Meeting with the University Chemical Society. Monday November 20th at 5 p.m. Lecture “Persulphate Oxidation of Carboxylic Acids,” by Dr.R. H. Thomson F.R.I.C. Friday December lst at 8.30 p.m. Lecture “Biphenylene and Related Compounds,” by Professor W. Baker D.Sc. F.R.S. Joint Meeting with the University Chemical Society. Monday December 4th at 5 p.m. Lecture “Some Hydrogen Transfer Reactions,” by Professor €3. B. Henbest Ph.D. F.R.I.C. Monday January 22nd 1962 at 5 p.m. Lecture “The Action of Alkylating Agents on Nucleic Acids and their Constituent Nucleotides,” by Dr. P. D. Lawley B.A. Cardiff (Meetings will be held in the Department of Chem- istry University College Cathays Park.) Monday October 30th 1961 at 5 p.m. Lecttlre “Some Recent Advances in Organo-phosphorus Chemistry,” by Dr. F. G. Mann F.R.I.C. F.R.S. Monday December 4th at 5 p.m.Lecture “Transfer Reactions of Oxygenated Radi- cals” by Professor A. F. Trotman-Dickenson Ph.D. Dublin (Meetings to be held in the Department of Chemistry Trinity College.) Wednesday November 22nd 1961 at 5.30 p.m. Lectare “The Stereochemistry of Flavan-4-ols,” by Professor Eva M. Pfiilbin D.Sc. Friday November 24th at 5.30 p.m. Lecture ‘‘Some New Photo chemical React ions ” by Professor D. H. R. Barton D.Sc. F.R.S. Joint Meeting with the Werner Society. Wednesday January 31st 1962 at 5.30 p.m. Lecture “Chemical Kinetics in Organic Chemistry,” by Professor E. D. Hughes DSc. F.R.S. Durham (Joint Meetings with the Durham Colleges Chemical Society to be held in the Science Laboratories The University.) Monday October 16th 1961 at 5 p.m.Lecture “Discoveries and Inventions,” by Dr. M. A. T. Rogers B.Sc. F.R.I.C. Monday November 13th at 5 p.m. Lecture “Surface Radiochemistry,” by Dr. S. J. Thompson B.Sc. Monday November 27th at 5 p.m. Lecture “Metals and /3-Diketones,” by Dr. M. R. Truter B.Sc. Monday December 1 lth at 5 p.m. Lecture “Seeing Molecules with Microwaves,” by Dr. J. Sheridan M.A. Monday January 29th 1962 at 5 p.m. Lecture “An Aspect of the Chemistry of Natural Products,” by Professor C. H. Hassall M.Sc. Edinburgh (Joint Meetings with the Royal Institute of Chemistry and the Society of Chemical Industry unless other- wise stated.) Thursday October 12th 1961 at 7.30 p.m. Lecture “Some Observations on the Chemistry of Human Blood-group Substances,” by Professor W.T. J. Morgan D.Sc. F.R.I.C. F.R.S. To be given at the Heriot-Watt College. Wednesday November 8th at 7.30 p.m. Lecture “Some Principles and Practices in Corrosion Protection,” by Dr. T. P. Hoar M.A. To be given at the IIerio t -Wa t t College. Tuesday November 28th at 4.30 p.m. Lecture “Hydrogen Bonding from a Crystallo-grapher’s Viewpoint,” by Dr. J. C. Speakman M.Sc. Joint Meeting with the University Chemical Society to be held in the Department of Chemistry The University. Thursday January 18th 1962 at 7.30 p.m. Lecture “Recent Advances in the Chemistry and Applications of Silicones,” by Dr. J. Stafford. To be given at Heriot-Watt College. Exeter (Meetings to be held in the Washington Singer Laboratories.) Friday October 20th 1961 at 5.15 p.m.Lecture “How Plants make Alkaloids,” by Dr. A. R. Batters by. Friday November 17th at 5.15 p.m. Lecture “Recent Developments in Acetylene-Allene Chemistry,” by Professor E. R. H. Jooes D.Sc. F.R.S. Joint Meeting with the University Chemical Society. Glasgow Thursday Octobcr 19th 1961 at 4 p.m. Lecture “Unusual Properties of the Nitrate Group,” by Professor C. C. Addison D.Sc. F.R.I.C. Joint Meeting with the Alchemist Club and the Ander- sonian Society to be held in the Chemistry Depart- ment The University. Friday November 17th at 4 p.m. Lecture “Some Aspects of Cholesterol Biosyn- thesis,” by Dr. G. J. Popjak F.R.S. Joint Meeting with the Alchemists Club to be held in the Chem- istry Department The University.PROCEEDINGS Friday December 8th at 7. I5 p.m. Lecture “The Structure of Natural Products by Direct %Ray Analysis,” by Professor J. Monteath Robertson D.Sc. F.R.I.C. F.R.S. Joint Meeting with the Royal Institute of Chemistry the Society of Chemical Industry and the Society for Analytical Chemistry to be held in the Royal College of Science and Technology. Hull (Meetings will be held in the Department of Chem- istry The University.) Thursday November 2nd 1961 at 5 p.m. Lecture “Molecular Addition Compounds,” by Professor N. N. Greenwood Ph.D. Sc.D. Joint Meeting with University Students Chemical Society. Thursday November 16th at 5 p.m. Lecture “Some Studies in the Porphyrin Field,” by Professor G.V?. Kenner Ph.D. Sc.D. Keele (Joint Meetings with the University College Science Society to be held in the Department of Chemistry University College of North Staffordshire.) Monday October 23rd 1961 at 5 p.m. Lecture “Inorganic Heterocycles,” by Mr. N. L. Paddock B.A. Tuesday November 7th at 8.30 p.m. Lecture by Dr. J. S. Anderson F.R.S. Tuesday November 21st at 8.30 p.m. Lecture “The Anatomy of the Chemist,” by Dr. T. S. Stevens A.R.I.C. Leeds (Meetings to be held in the Chemistry Lecture Theatre The University.) Thursday October 12th 1961 at 6.30 p.m. Lecture “A Re-examination of the Octet Rule,” by Dr. J. W. Linnett M.A. F.R.S. Thursday November 30th at 6.30 p.m. Lecture “Aspects of the Biosynthesis of Phenolic Compounds,” by Professor C.H. Hassall M.Sc. Leicester (Joint Meetings with the University Chemical Society to be held in the University.) Monday November 20th 1961 at 4.30 p.m. Lecture “Some Applications of Electron-spin Resonance Spectroscopy,” by Professor H. C. Longuet-Higgins M.A. D.Phil. F.R.S. Tuesday December 5th at 4.30 p.m. Lecture “Some Recent Observations on the Activity of Metal Catalysts,” by Professor C. Kernball M.A. Ph-D. F.R.I.C. SEPTEMBER 1961 Monday January 22nd 1962 at 4.30 p.m. Lecture “The Surface of an Oxidising Metal,” by Dr. J. S. Anderson F.R.S. Liverpool (Joint Meetings with the Student Chemical Society to be held in the Department of Inorganic and Physical Chemistry The University.) Thursday October 26th 1961 at 5 p.m.Lecture “Alkaloid Biosynthesis,” by Dr. A. R. Battersby. Thursday November 23rd at 5 p.m. Lecture “Some Aspects of Structure and Reactivity in Ionic Solutions,” by Professor K. W. Sykes M.A. D .Phil. Thursday January 25th 1962 at 5 p.m. Lecture “Structure-Activity Relationships among the Penicillins and Cephalosporins,” by Dr. E. P. Abraham M.A. F.R.S. Manchester Thursday October 19th 1961 at 6.30 p.m. Lecture Organonietallic Peroxides,” by Dr. A. G. Davies. To be given in Room F1 Manchester College of Science and Technology. Tuesday November 14th at 6.30 p.m. Centenary Lecture “Some Reactions of Free Radicals,” by Professor G. B. Kistiakowski. To be given in Room Fl Manchester College of Science and Technology.Thursday November 16th at 5 p.m. Lecture “The Biogenesis of Alkaloids,” by Sir Robert Robinson O.M. D.Sc. F.R.S. Joint Meet- ing with the Students Union Chemical Society of Royal College of Advanced Technology Salford to be held in the Conference Hall of the College. Thursday December 7th at 6.30 p.m. Oficial Meeting and Lecture “The Structure of Proteins,” by Dr. M. F. Perutz F.R.S. To be held in Room F1 Manchester College of Science and Technology. Thursday January 25th 1962 at 6.30 p.m. Lecture “Recent Developments in Analytical Chemistry,” by Professor R. Belcher Ph.D. F.R.I.C. Joint Meeting with the Royal Institute of Chemistry and the Society of Chemical Industry to be held in Room F1 Manchester College of Science and Technology.Newcastle upon Tyne (Meetings will be held in the Chemistry Department King’s College.) Thursday October 19th 1961 at 6.30 p.m. Lecture “Oxidation of Organic Compounds. Some Recent Work,” by Professor H. B. Henbest Ph.D. F.R.I.C. Joint Meeting with the Royal Institute of Chemistry. Friday October 27th at 5.30 p.m. Bedson Club Lecture “Selective Utilisation of Metabolic Routes by E. coZi.,” by Professor A. L. Kornberg M.D. Monday November 20th at 5.30 p.m. Lecture “Free Radicals in Irradiated Crystals,” by Dr. D. H. Whiffen M.A. Friday December lst at 5.30 p.m. Bedson Club Lecture “The Gibberellins a New Group of Plant Hormones,” by Dr. P. W. Brian F.R.S. Northern Ireland (Joint Meetings with the Royal Institute of Chem- istry and the Society of Chemical Industry to be held in the Chemistry Department David Keir Building Queen’s University Belfast.) Tuesday October loth 1961 at 7.15 p.m.Royal Institute of Chemistry Lecture “The Mechan- ism of Detergent Action,” by Professor N. K. Adam M.A. Sc.D. F.R.S. Tuesday October 24th at 7.45 p.m. Lecture “z-Bonding in Three-co-ordinate Boron-Nitrogen Systems,” by Dr. M. F. Lappert F.R.T.C. Thursday November 23rd at 7.45 p.m. Lecture “Some Aspects of Tannin Chemistry,” by Professor R. D. Haworth D.Sc. F.R.S. Tuesday January 16th 1962 at 7.45 p.m. Lecture “Unimolecular Gas Reactions,” by Profes- sor A. F. Trotman-Dickenson Ph.D. North Wales Thursday October 12th 1961 at 5.45 p.m.Lecture “Forensic Science,” by Dr. F. G. Tryhorn F.R.I.C. Joint Meeting with the University College Chemical Society to be held in the Chemistry Department University College Bangor. Nottingham (Joint Meetings with the University Chemical Society to be held in the Department of Chemistry The University.) Tuesday October 31st 1961 at 5 p.m. Lecture “The Structure and Function of Bacterial Cell Walls,” by Professor J. Baddiley D.Sc. F.R.S. Tuesday November 14th at 5 p.m. Lecture “Experimental Methods in the Study of Chemical Kinetics,” by Professor J. C. Robb Ph.D. F.R.I.C. Tuesday November 28th at 5 p.m. Lecture “Some Chemical Applications of Electron Resonance Spectroscopy,” by Professor H. C Longuet-Higgins M.A.D.Phil. F.R.S. Oxford (Joint Meetings with the Alembic Club to be held in the Inorganic Chemistry Lecture Theatre.) Monday October 16th 1961 at 8.15 p.m. Lecture “The Synthesis of Heterocyclic Phosphorus Compounds Some Successes and Failures,” by Dr. F. G. Mann F.R.I.C. F.R.S. Monday October 30th at 8.15 p.m. Lecture “Free Radicals in Crystals,” by Dr. D. H. Whiffen M.A. Monday November 13th at 8.15 p.m. Lecture “Some Aspects of the Chemical Structure of Proteins,” by Professor H. D. Springall M.A. D.Phil. F.R.I.C. Monday November 27th at 8.15 p.m. Lecture “Some Hydrido-complexes of Transition Metals,” by Dr. J. Chatt F.R.S. Reading Wednesday January Mth 1962 at 6.15 p.m. Official Meeting and Tilden Lecture “Hydrido- and Related Organo-complexes of Transition Metals,” by Dr.J. Chatt F.R.S. To be held in the University. St. Andrews and Dundee (Joint Meetings with the University Chemical Society to be held in the Chemistry Department The University St. Andrews.) Friday October 20th 1961 at 5.15 p.m. Lecture “Alchemy Instrument of Culture,” by Professor J. Read M.A. Sc.D. F.R.S. Friday October 27th at 5.15 p.m. Lecture “Big Rings,” by Professor R. A. Raphael D.Sc. Ph.D. F.R.I.C. Friday November 1 Oth at 5.15 p.m. Lecture “Chemical Relationships between Brewing Beer and Baking Bread,” by Dr. M. A. Pyke. Friday November 24th at 5.15 p.m. Lecture “New Reactions in Dinitrogen Tetroxide,” by Professor C. C. Addison Ph.D. F.R.I.C.Friday January 19th 1962 at 5.15 p.m. Lecture by Dr. H. C. S. Wood B.Sc. Shefiield (Joint Meetings with the Royal Institute of Chem-istry and the University Chemical Society to be held in the Department of Chemistry The University.) Thursday November 16th 1961 at 4.30 p.m. Lecture “Polynuclear Complex Formation in Solution,” by Dr. F. J. C.Rossotti M.A. Thursday November 30th at 4.30 p.m. Lecture “The Electronic Structures of Some Molecules and RadicaIs,” by Dr. J. W. Linnett MA. F.R.S. PROCEEDINGS Southampton Friday October 13th 1961 at 7 p.m. Lecture “The Chemistry of Wines and Spirits,” by Dr. E. C. Barton-Wright F.R.I.C. Joint Meeting with the Portsmouth and District Chemical Society to be held in The College of Technology Ports- mouth.Friday October 20th at 5 p.m. Lecture “Experimental Methods for the Study of Reaction Kinetics,” by Professor J. C.Robb D.Sc. Ph.D. Joint Meeting with the University Chemical Society to be held in the Chemistry Department The University. Friday November 3rd at 5 p.m. Lecture “Addition Accompanying Substitution in the Halogenation of Aromatic Compounds,” by Professor P. B. D. de la Mare Ph.D. Joint Meeting with the University Chemical Society to be held in the Chemistry Department The University. Friday November 17th at 5 p.m. Lecture “The Rapid Reactions of Some Complex Ions,” by Dr. R. G.Wilkins. Joint Meeting with the University Chemical Society to be held in the Chemistry Department The University. Friday January 26th 1962 at 7 p.m.Lecture “Reactions of Highly Excited Molecules,” by Dr. H. M. Frey M.A. Joint Meeting with the Portsmouth and District Chemical Society to be held in The College of Technology Portsmouth. Swansea (Joint Meetings with the University College Chemical Society to be held in the Department of Chemistry University College.) Monday October 30th 1961 at 4.30 p.m. Lecture “Chemotherapy,” by Dr. F. L. Rose O.B.E. F.R.I.C. F.R.S. Monday November 13th at 4.30 p.m. Lecture “Recent Advances in Nuclear Resonance,” by Dr. R. E. Richards M.A. F.R.S. Monday January 29th 1962 at 4.30 p.m. Lecture “Fast Reactions,” by Professor G. Porter M.A. Ph.D. F.R.S. Tees-side Wednesday October 18th 1961 at 8 p.m. Exhibition of Scientific Films.Joint Meeting with the Royal Institute of Chemistry and the Society of Chemical Industry to be held at the Synthonia Theatre Billingham. Friday November 10th at 8 p.m. Lecture “Aspects of Chemistry of Olefin Complexes SEPTEMBER 1961 of Transitional Metals,” by Professor G. Wilkinson Ph.D. F.R.I.C. Joint Meeting with the Royal Institute of Chemistry and the Society of Chemical Industry to be held at the William Newton School Norton. 35 1 Tuesday November 28th. Official Meeting and Lecture “Means to Some Ends,” by Professor C. L. Wilson D.Sc. F.R.I.C. To be held at the Constantine Technical College Middlesbrough. APPLICATIONS FOR FELLOWSHIP (Fellows wishing to lodge objections to the election of these candidates should communicate with the Honorary Secretaries within ten days of the publication of this issue of Proceedings.Such objections will be treated as confidential. The forms of application are available in the Rooms of the Society for inspection by Fellows.) Ahmad Towhida MSc. Department of Pharmacology The University Glasgow W.2. Baum Burton Murry B.S. 4400 Centre Avenue Pitts- burgh 13 Pennsylvania U.S.A. Boggs Norman Towae. Woodstock New York U.S.A. Brown Allan Guildford A.R.C.S.T. 70 Carmyle Avenue Tollcross Glasgow E.2. Cain Maurice Edward M.Sc. 1 Byfield Welwyn Garden City Herts. Chapman Andrew Colin Ph.D. A.1nst.P. 9 Carlton Avenue Wollescote Stourbridge Worcs. Chen Chung-yuan B.Sc. School of Chemistry Sydney University New South Wales Australia.Chia Lawrence Hock Leong B.Sc. University Hall 281 Parramatta Road Glebe New South Wales Australia. Coulter Andrew Kenneth. 113 Chalkwell Road Sitting- bourne Kent. Cox Hollace Lawton B.A. Chemistry Department Indiana University Bloomington Indiana U.S.A. Craig Robert Arrol M.Sc. Lincoln College Oxford. Dale David Henry B.Sc. Wadham College Oxford. Del Hierro Eduardo Sc.D. Calle 56 No. 18-20 Bogota, Colombia South America. Fosker Alan Philip B.Sc. 36 Jersey Road Hounslow Middlesex. Goodby John Malcolm BSc. A. Boake Roberts & Co. Ltd. Carpenters Road Stratford London E.15. Gordon Robert Dixon M.Sc. Department of Chemistry, University College London W.C.L. Gray Angus John B.Sc. 22 Meadow Road Claygate Esher Surrey.Griffin Reginald Edward. 80 Whittucks Road Hanham Bristol. Gutmann Viktor Ph.D. Institut fur Anorganische und Allgemeine Chemk Technische Hochschule Vienna VI Austria. Hearne Margaret Rose. 52 Trelawney Street Eastwood Sydney New South Wales Australia. Hilder Martin Hugh B.Sc. 19 Bentley Way Woodford Wells Essex. Ikeda Hiroshi. Rikagaku-kenkyujo Komagome Kami- fujimaecho Bunkyo-ku Tokyo Japan. Jagger Anthony Hainsworth Ph.D. Flat 1,401 Foleshill Road Coventry Warwickshire. Johns John Hywel Thomas Ph.D. 6~ Silver Street Bridgwater Somerset. Johilson Sidney Thomas B.Sc. A.R.I.C. 38 Osborne Road ,Hartsh ill Stoke-on-Tren t. Keglevic Dina Ph.D. Tracer Laboratory Institute “Ruder Boskovic” Bijenicka 54 Zagreb Yugoslavia.Khan Nasim Alam B.Sc. Buxly Paints Ltd. S.I.T.E. Mangopir Road Karachi 16 Pakistan. Kover Warner Bruce B.S. Gates and Crellin Laborator- ies California Institute of Technology Pasadena California USA. Kramer Karlheinz Alfred Walter Dr.rer.nat. 6 Kirby Close Upton Park Chester. Lane Stuart Michael B.S. Department of Chemistry Brandeis University Waltham 54 Massachusetts, U.S.A. Marshall Geoffrey B.Sc. 54 St. Andrews View Chaddes- den Derby. Neuman Robert Canute Jr. B.S. Department of Chemistry California Institute of Technology, Pasadena California U.S.A. Newman Gerald Alan B.Sc. Green Lane Farm, Caenvent nr. Chepstow. Niederprum Hans Dr.rer.nat. 406 Narborough Road Leices ter . Patel Vithalbhai Chaturbhai M.Sc. Chemistry Depart- ment Battersea College of Technology London s.w.ll.Pratt Arthur James B.Sc. Maen Gwyn Pen-y-Bryn Road Colwyn Bay N. Wales. Richardson Bernard John B.Sc. 156 Runnymede, Merton London S.W.19. Ritchie Geoffrey Lewis Deans M.Sc. Flat 9 Homer Court 49 High Street North Sydney New South Wales Australia. Saxby John Duncan. St. Andrew’s College Newtown New South Wales Australia. Smith David Carroll B.Sc. 10 Grange Hill Edgware Middlesex. Thompson Walter Keith A.R.I.C. 10 Marina Gardens Felixstowe Suffolk. Turner John Cameron Ph.D. Biorex Laboratories Ltd. 198 City Road London E.C.1. Wharton John Jardine B.Sc. 41 Acacia Avenue Hale Cheshire. Willick Gordon Edward B.Sc. Department of Bio- chemistry University of British Columbia Vancouver 8 B.C.Canada. Wood Harry Burgess Jr. Ph.D. National Institutes of Health Bethesda Maryland U.S.A. Wood John Stanley B.A. Chemistry Department University College of North Staffordshire Keele Staffordshire. PROCEEDINGS OBITUARY NOTICES HUBERT THOMAS STANLEY RRITTON 1892-1 960 STANLEY HUBERTTHOMAS BRITTONdied at his home at Crawley Sussex on December 30th 1960 at the early age of 68. He is survived by his son and daughter. Born at Kingswood near Bristol on April 22nd 1892 the son of a local shoemaker he was educated at the village school and passed thence by scholarship to St. George’s Grammar School Hanham; after a period as pupil teacher he obtained a scholarship to Merchant Venturer’s College and later to Bristol University graduating in 1914.After a short period as Chemistry Master at Sexe’s School Bruton he was called up for service as a chemist in the Aero- nautics Inspection Department where he remained till in 1920 he became Assistant Lecturer at King’s College London. From 1925 to 1927 he held a senior D.S.I.R. award in Professor Philips’ Depart- ment at Imperial College where he continued the researches in electrochemistry which he had com-menced at King’s and in 1926 was awarded the D.Sc. of London University. In 1928 after a few months of unemployment he was appointed Lecturer at Norwood Technical College and in the following year joined the staff of the Chemistry Department at the then University College of the South West of England; here he remained for the rest of his profes-sional Me first as lecturer and then from 1935 onwards as Professor of Chemistry.On his retire- ment in 1957 he was made Emeritus Professor. Throughout his career as University teacher Britton maintained a nice balance between his teach- ing and his research interests. Whether because of his early experience of schoolteaching or from a natural aptitude he enjoyed teaching and was a lively lecturer who established ready rapport with his audience; he was greatly liked by his students who hvere attracted by the sceptic in him-“doubting Thomas” was a description he frequently used of hiniself-and by his warm humanity. His published research dates from his earliest years at King’s College for already in 1921 he had published in collaboration with Professor A.J. Allmand his first paper which described a phase- rule study of the system potassium sulphate-beryl- lium sulphate-water. This started him on the road he was to follow for the rest of his life-a study of homogeneous and heterogeneous ionic equilibria particularly in their relevance to analytical chemistry. His first encounter with beryllium soon led him to a detailed study of its separation from aluminium. At that time beryllium was one of the less familiar elements and his early acquaintance with it appears to have stimulated his interest in other of the less- common or rare elements. Whilst still at King’s College he undertook a quantitative investigation of a number of the reactions involved in the separation of the rare ezrths.Though he did not originate any new electrode systems he developed and extended the use of the hydrogen oxygen antimony tungsten and glass electrodes to the investigation of some common precipitation reactions-e.g. the pi-ecipita- tion of the hydroxides of magnesium manganese iron cobalt and nickel-about which quantitative knowledge was but scanty. Extension of these studies to the precipitation of basic salts and the salts of less-common acids such as molybdic and tungstic naturally followed. Though his favourite experimental technique was potentiometric he also made extensive use of con- ductometric measurements and pioneered the appii- cation of optical rotation to titrimetry.The Britton- Robinson universal buffer is known to all whilst within the covers of “Hydrogen Ions,” which ran into four editions there is to be found a wealth of information on a wide range of topics all bearing the stamp of illtimate personal acquaintance. Britton was a prodigiously hard worker and nearly a hundred papers came from his pen; eighteen of these indeed were already published whilst he was still assistant lecturer at King’s College. In his early days at Exeter despite his onerous teaching duties- he was then responsible for all the honours courses in physical and inorganic chemistry-he continued to carry out an impressive amount of research work and to direct the work of a number of research students; during this period he also wrote “Con- ductometric Analysis,” brought out the Second Edi- tion of “Hydrogen Ions,” and produced “Chemistry Life and Civilization,” a book of a general natuic based on his extra-mural lectures.During the war of 1939-45 his energies were largely absorbed in teaching in his duties as Dean of the Faculty of Science and as Senior Gas Adviser for Devon and Cornwall and in acting as host to evacuated departments from London. After the war the demands of a rapidly growing Department drew him to his great regret more and more away from the bench and the library; but he still maintained a lively interest in research and directed the work of research students until he rctired. He had hoped to write up this work during his retirement but his life then was clouded by anxiety over the failing health SEPTEMBER 1961 of his wife who predeceased him by eighteen months.Throughout his professional life Britton was actively interested in the work of the Chemical Society the Society of Chemical Industry and the Royal Institute of Chemistry; he served at one time or another on the Councils of all three bodies and did much to encourage his students to join and support them. Britton was a man whom to know was to like and respect. He was outstandingly human warmhearted and friendly and his sage advice his encouragement and help were freely given to student and colleagues alike and were as freely sought and highly valued. His sudden death from cerebral haemorrhage came as a great shock to all who knew him for he re- mained in full vigour taking his usual lively interest in his fellow men and affairs till his final brief illness.He will live long in the affectionate memory of the many students who passed through his hands and of all those who knew him. S. J. GREGG. CECIL JOHN TURRELL CRONSHAW 1890-1961 THEschool of organic chemistry which W. H. Perkin built up at Manchester over the years 1892-1912 gave several notable recruits to the British dyestuffs industry. None however was so outstanding as Cecil John Turrell Cronshaw a Fellow of the Society since 1926 who died in Manchester on January 5th 1961. Cronshaw entered the industry in 1915 when it was at the height of the improvisation and con- fusion which followed the sudden interruption of the supplies of dyestuffs from Germany at the outbreak of war and in face of demands on staff which can scarcely be imagined today and his ability was quickly recognised by Dr.Herbert Levinstein then Managing Director of Levinstein’s Ltd. When in little more than ten years the British Dyestuff’s Cor- poration Ltd. formed by amalgamation under Governmefit pressure between Levinstein’s Ltd. and British Dyes Ltd. had itself become a founder member of Imperial Chemical Industries Limited Cronshaw was already Technical Director. With Mr. James Baddiley he undoubtedly made the biggest individual contribution to the re-establishment of the dyestuffs industry in this country after the first World War.Indeed it may be not too much to say that without Cronshaw’s vision and enthusiasm his determination his courage in taking decisions his skill as a negotiator throughout the troubled years following the Sankey judgment and in the con-troversy over the renewal of the Dyestuffs (Import Regulation) Act the industry might well have col- lapsed again. His contribution to the discussion at the British Association meeting at Bristol in 1930 when the Government wavered and the renewal of the Act was in balance and still more his organisa- tion are factors which should not be forgotten. He fought with tempered judgment for an adequate research programme as the essential basis for such an iiidustry in times when finance was hard to find and he recognised the close relation of research on dyestuffs and intermediates to organic research generally.His vision did much to promote a better understanding between scientists in industry and in the universities to their mutual advantage. The working arrangements he established for the Dye- stuffs Division of Imperial Chemical Industries Limited beginning with the Dyestuffs Group Re- search Committee and comprising successively a Technological Committee a Pest Control Research Committee and a Medicinal Products Panel stimulated similar arrangements elsewhere and though modified remain a notable feature of the organisation which his outstanding administrative ability created. Born in Heywood in 1890 Cronshaw was educated at Bury Grammar School of which he subsequently became a Governor and he was then apprenticed for three years to J.H. Lester in the testing house of the Manchester Chamber of Commerce before proceed- ing in 1910 to Manchester University where he graduated with First Class Honours in Chemistry in 1913. He then worked as research chemist with Strange and Graham Ltd. in London where he developed Fernbach’s fermentation process and was one of the first to make synthetic rubber in any quantity from butadiene. In 1915 he joined Levin- stein Ltd. as research chemist and after some ex- perience in oleum manufacture he was placed in charge of the indigo factory of Meister Lucius and Bruning at Ellesmere Port which Levinstein Ltd. had acquired in 1916.This factory had been built to operate on phenylglycine imported from Germany but there was no plant for the manufacture of this intermediate at Ellesmere Port. Manufacture was improvised at Levinstein’s Blackley works and within three months in November 1916 the first batch of wartime indigo was manufactured at Ellesmere Port. The following year Cronshaw whose flair for administration was now as apparent as his courage and resource was sent to the United States to negotiate the exchange of technical information betwcen Levinstein Ltd. and Messrs. Du Pont de Neniours. In 1918 after the Armistice he was ap- pointed Chemical Controller of the factories in the British Rhineland occupational area an experience which undoubtedly widened his understanding of the structure and organisation of organic chemical industry in Germany.When in 1919 he returned to England Cronshaw was appointed chief administrative assistant to Dr. Levinstein now joint Managing Director of the British Dyestuffs Corporation Ltd. With his further position as head of the newly formed Production Control Department Cronshaw was now at the administrative centre and there he remained. His membership from 1926 to 1934 of the Dyestuffs Industry Development Committee deepened his insight and strengthened his influence. Cronshaw’s central position was scarcely affected when in 192 1 he became Works Manager at Blackley a position he held until 1924 when he was appointed Technical Manager of the British Dyestuffs Cor- poration Ltd.In those three years Cronshaw did much to foster the development of the manufacture of organic accelerators for the vulcanisation of rubber which had begun at Blackley mainly about the end of 1922. Cronshaw’s interest in rubber chemicals doubtless originated in his early experience with synthetic rubber and in the period 1923-27 he took out jointly with Dr. W. J. S. Naunton some nine British patents in this field. They cover the manufacture of diarylguanidines triphenylguani- dines metallic xanthates and diarylalkoxycarbonyl- thioureas and other improvements in the vulcanisa- tion of rubber and apart from B.P. 278,465 (with J. Baddiley and E. Chapman) for improvements in friction surfaces these specifications represent Cronshaw’s sole direct contribution to new know- ledge.Cronshaw’s indirect contribution however is immeasurable and it is sufficient to quote the citation accompanying the award to him in 1960 of the Perkin Medal of the Society of Dyers and Colourists “As a leader under whose enthusiastic guidance the phthalocyanine pigments and derived textile dyes were first made available and their basic constitution determined.” By now however the British Dyestuffs Corpora- tion had become a “founder member’’ of Imperial Chemical Industries Limited and in 1926 Cronshaw was Technical Director becoming subsequently in 1931 joint Managing Director with Dr. John Thomas of the Dyestuffs Group now known as the Dyestuffs Division On the death of Dr.Thomas in 1933 Cronshaw was sole Managing Director and held this post until in 1939 he became Chairman. From 1943 to September 1952 when he retired he was a Director of the main Board. No outline of Cronshaw’s career in industry can convey an impression of his dynamic personality the vitality of his ideas or the rapidity with which he could grasp the essentials of the most complicated PROCEEDINGS situation. Shortness of stature was never a handicap to him or hindered him taking his place in discussion. To young chemists he gave warm and generous encouragement though his selection and handling of men scarcely matched his superb technical judgment and administrative skill. Something of the quality of his mind and the width of his outlook may be gathered from the addresses and lectures he delivered usually on some aspect of the industry he loved.“The Seven Lamps of Enterprise”-his Chairman’s address to the Manchester Section of the Society of Chemical Industry in 1927; “In Quest of Co1our”-the 1935 Jubilee Memorial Lecture of that Society “Pattern for Industry”-the 1945 Mather Lecture to the Textile Institute; the 1948 Dalton Lecture to the Royal Institute of Chemistry “Through Chemistry Adornment,” and his address to The Literary and Philosophical Society of Manchester “Some Ac- count of a Research Adventure within the Industrial Pattern”-these all display the penetration of his thought but hardly project a personAity that prob- ably found its best expression in the cut and thrust of discussion or debate.Cronshaw was a Vice-President of the Society of Chemical Industry 1935-38 and Chairman of the Manchester Section 1927-29. He was President of the Society of Dyers and Colourists 193947 to which he rendered outstanding service his address ‘‘Ourselves and our Society” in 1937 pointing to activities in which as in comments on technological education he was ahead of his time. His honours included an Honorary Doctor of Science from the University of kds (1938) a Silver Medal of the Royal Society of Arts and the Hinchley Medal of the British Association of Chemists (1960) but the honour he most valued was his office as Prime Warden of the Worshipful Company of Dyers (1950-55) of which Company he was elected a member in 1928.Besides serving on the Board of Management of the British Colour Council 193545 he was a director of the Manchester Ship Canal (1940) of the District Bank and of the North Western Gas Board. He also rendered services on the University Court and to the Chemistry Com- mittee of the Manchester College of Technology which were greatly valued. Riding and latcr sailing were his chief relaxation though he played a fair game of golf and at one time of bridge and was to be found at Old Trafford and Hall6 concerts when leisure allowed. Apart from books on horses and riding biography was his chief interest in reading and often provided him with quotations that surprised his audience. Cronshaw was survived by a widow who died 3 months later and two sons.R. BRIGHTMAN. SEPTEMBER 1961 355 EDWARD DE BARRY BARNETT 1886-1 961 DE BARRYBARNETT, EDWARD who died in London on March 23rd 1961 in his 75th year did much to enhance the high reputation of the Chemistry De- partment of the Sir John Cass Technical Institute where he was appointed Lecturer in Organic Chemistry in 19 19 and became successively Head of the Department of Organic Chemistry Head of the Department of Chemistry and Deputy Principal. He retired in 1947. His previous experience as an industrial chemist which included appoint- ments with Levinstein The Nobel Explosives Company at Ardeer The National Explosives Company at Hayle in Cornwall and The British Drug Houses provided a very valuable foundation for his teaching career and helped to attune him to the outlook needs and problems of the part-time students with whom he was mainly concerned.He devoted himself with a zealous enthusiasm to the chemical education of his students to an extent which went far beyond the requirements of duty. Attend- ance at his “tutorials” was a much sought-after privilege. In the 1920’s all teaching at the Sir John Cass Institute was conducted in the evening and a typical day for Barnett would be an intensive morning’s work in the Society’s Library an afternoon spent at the bench on his personal researches followed in the evening by four hours of strenuous teaching. His lectures could be heard well beyond the confines of the lecture room and he saw to it that the evening’s work was just as strenuous for his students most of whom had already done a full day’s work as for himself.Reading writing and preparation of lectures usually occupied his week-ends. In his last industrial post he had been the victim of a serious accident involving burning benzyl chloride. This led him to turn his attention to teaching as he felt that his health was too impaired for the rigours of life of a works chemist ! Barnett was born at St. Leonards-on-Sea on October 20th 1886 and was educated at Malvern College and University College London. He graduated with first-class honours in chemistry in 1908 and remained for a further two years at the College where he conducted research on organic sulphur compounds in collaboration with the late Samuel Smiles.A blow with a cricket ball at the age of 13 was probably responsible for the deafness which became an increasing infliction during his life and severely handicapped him in his career. It was responsible for some of his characteristic manner- isms including his habit of parrying any statement which he had not heard or had heard imperfectly with a drawling “Wha-at?” The bellowing tone in which the question was put was terrifying to the timid. Tall and well-built but of sallow complexion full of physical and mental vigour this hawk-nosed glassy-eyed figure was a dominating personality in any company. He did not take kindly to criticism or to obstruction but could be a very loyal and warm- hearted friend with a rather mischievous sense of humour.He was a good raconteur and was fond of relating experiences which he had found amusing and especially those in which he had scored over officialdom or had outwitted authority. A certain aloofness and shyness caused him to shun female company and he was unmarried; but he could be a very entertaining companion. Barnett enlisted in the Royal Engineers after the outbreak of the 1914 war but was soon discharged on medical grounds. He subsequently served in France with the British Ambulance Association. With his avidity for work Barnett was a prolific writer of chemical books. His “Explosives” and “Coal-Tar Dyes and Intermediates” were stimulated by his industrial experience whereas “Organic Analysis” (with P.C. L. Thorne) “Inorganic Chemistry’’ (with C. L. Wilson) and “Mechanism of Organic Chemical Reactions” were intended to assist his students. His monograph “Anthracene and Anthraquinone” published in 1921 was a mine of information and became a classic. It was the writing of this book which determined his major research interests and he published about a hundred original papers of which the more important dealt with the chemistry of anthracene and its simple derivatives. He took his D.Sc. degree of London University in 1926. Using anthracene as a model he made a wide study of additions to unsaturated systems and he investigated extensively the influence of substitution on the reactivity of the meso-positions of anthracene and its dihydro-derivatives.This led him (with his collaborators) to the discovery of a series of anionotropic transformations of a novel and unique character but his natural conservatism caused him to recoil from the theoretical implica- tions of his results and for some time he was reluc- tant to accept their true interpretation. An interesting new reaction which with the present writer he discovered was the addition of pyridine perbromide and pyridine salts to certain types of unsaturated molecules. A minor piece of work the reduction of an obsolete commercial dyestuff Sirius Yellow G resulted in the preparation of 1,2-benzanthracene the availability of which subsequently played an important part in the discovery of the carcinogenic hydrocarbons.Whether or not it was due to his Scottish maternal ancestry Barnett had a streak of caution in his character and an economical approach to his scientific work. His choice of a research subject was often influenced by the cost of the requisite chemicals. He would spend weeks fractionating commercial coal tar bases to prepare a supply of pure pyridine- and sell the by-products to defray the cost of the still. Many young chemists including the present writer who was associated with him in the 1920's and budding chemists owed much to the kindly and stimulating interest of this unusual character. J. W. COOK. ADDITIONS TO THE LIBRARY The tercentenary celebrations of the Royal Society of London 1960.Edited by Sir Harold Hartley. Pp. 142. Royal Society. London. 1961 (Presented by the pub- lishers.) L'opera scientifica di Stanklao Cannizzaro. M. Giua. Pp. 23. Stabilimento Grafico Impronta. Torino. 1961. (Presented by the publlsher.) The French chemical industry J. J. Beattie. Pp. 20. D.S.I.R. London. 1961. (Presented by the publisher.) Handbook of chemistry. Edited by N. A. Lange. loth edn. Pp. 1969. McGraw-Hill. New York. 1961. Physical properties of chemical compounds-1 1 1. Compiled by R. R. Dreisbach. (Advances in Chemistry Series No. 29.) Pp. 489. American Chemical Society. Washington. 1961. The crystal chemistry of some sodium polysulphides. 0. Erametsa and K. Karlsson. (Acta Polytechnica Scandinavica chemistry including Metallurgy Series No.15.) Pp. 17. Finnish Academy of Technical Sciences. Helsinki. 1961. (Presented by the publisher.) Radiation chemistry of gases. S. C. Lind. (American Chemical Society Monograph Series No. 151.) Pp. 313. Reinhold. New York. 1961. (Presented by the publisher.) Surface activity. J. L. Moilliet B. Collie and W. Black. 2nd edn. Pp. 518. Spon. London. 1961. (Presented by the publisher.) Surface activity and detergency. Edited by K. Durham. Pp. 250. Macmillan. London. 1961. (Presented by the editor.) The organic chemistry of boron. W. Gerrard. Pp. 308. Academic Press. London. 1961. (Presented by the author.) Azo and diazo chemistry; aliphatic and aromatic compounds. H. Zollinger. (Translated by H. E. Nursten.) Pp.444.Interscience. New York. 1961. Cyclic j3-diketones. G. Vanaga. Pp. 372. &ad. Nauk S.S.R. Riga. 1961. Ageratochromene a heterocyclic compound from the essential oil of Ageratum houstonianum. Mill. A. R. Alertsen. (Acta Polytechnica Scandinavica Chemistry including Metallurgy Series No. 13.) Pp. 56. Royal Norwegian Council for Scientific and Industrial Research. Oslo. 1961. (Presented by the publisher.) Reagent chemicals; American Chemical Society specifications 1960. Pp. 564. A.C.S. Washington. 1961. Treatise on analytical chemistry. Edited by I. M. Kolthoff and P. J. Elving. Vol. 1. Part 2. Pp.471. Inter-science. Publ. lnc. New York. 1961. Toxicology mechanisms and analytical methods. Edited by C. P. Stewart and A. Stolman.Vol. 2. Pp. 921. Academic Press. New York. 1961. Molecular structure and biological specificity a symposium sponsored by the Om of Naval Research and arranged by the American Institute of Biological Sciences held in Washington D.C. 1955. Edited by L. Pauling and H. A. Itano. Pp. 195. American Institute of Biological Sciences. Washington D.C. 1957. Proceeding of the Second Conference on Analytical Chemistry in Nuclear Reactor Technology Gatlinburg Tennessee 1958. Sponsored by the Oak Ridge National Laboratory. 3 Vols. Atomic Energy Commission Tech- nical Information Service. Oak Ridge Tennessee. 1959. Proceedings of the third conference on Analytical Chemistry in Nuclear Reactor Technology Gatlinburg Tennessee 1959. Sponsored by the Oak Ridge National Laboratory.(Talanta 1960 vol. 6.) Pergamon Press. New York. 1960. International symposium on biologically active mucoids held in Warsaw 1959. Sponsored by the Polska Akademia Nauk. Pp. 117. Polska had. Nauk. Warsaw. 1959. (Presented by Prof. W. T. .I.Morgan.) The protection of gas plant and equipment from corrosion joint symposium organised by the Corrosion Group of the Society of Chemical Industry the Institu- tion of Gas Engineers and the College of Advanced Technology Birmingham held 1960. Pp. 20. Society of Chemical Industry. London. 1961. (Presented by the publisher.) Proceedings of the Fourth Conference on Analytical Chemistry in Nuclear Reactor Technology Gatlinburg Tennessee 1960. Sponsored by the Oak Ridge National Laboratory.Pp.427. Atomic Energy Commission Tech- nical Information Service. Oak Ridge Tennessee. 1960. Causes of variation in chemical analyses and physicai tests of Portland cement. B. L. Bean and J. R. Dise. Issued by the United States National Bureau of Standards. N.B.S. Monograph 28. Pp. 24. U.S. Government Printing Office.Washington. 1961. (Presented by the publisher.) Biochemists' handbook. Edited by C.Long. Pp. 1192. Spon. London. 1961. (Presented by the publisher.) The analytical chemistry of beryllium proceedings of a symposium held at Blackpool 1960; organised by the Chemical and Metallurgical Services Dept. U.K.A.E.A. Production Group. Edited by J. Metcalfe and J. A. Ryan. Pp. 180 U.K.A.E.A. Warrington Lancs. 1961. NEW JOURNALS Journal of Structural Chemistry (U.S.S.R.).EngIish translation of Zhurnal Strukturnoi Khimii from 1960,l. Kinetics and Catalysis English translation of Kinetika y Katizos from 1960 1. Canadian Journal of Physics from 1961,39. Journal of Chemical Documentation from 1961 1.
ISSN:0369-8718
DOI:10.1039/PS9610000321
出版商:RSC
年代:1961
数据来源: RSC
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